Guanosine pentaphosphate - review (2023)

Related terms:

  • fatty acids
  • amino acids
  • Rybosomy
  • guanosine triphosphate
  • Biotin
  • Hydrolaza
  • Guanozyno-3'-diphosphoran 5'-diphosphoran
  • Sintetaza
  • Acetyl Coenzyme Carboxylase
  • receptor protein
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Pathogenesis of Streptococcus suis - Different virulence factors for zoonotic lifestyle

Greg Tramwaj, ... John M. Atack, dAdvances in microbial physiology, 2021

7.4 Alarm indication: RelA, RelQ and CodY

Accumulationguanosine pentaphosphate(ppGpp) often serves as an "alarm", a stress response signal (Irving, Choudhury i Corrigan, 2020). The production of ppGpp by RelA is triggered in response to stress, such as amino acid or carbon deficiency (Magnusson, Goodbye and Nystrom, 2005). Two ppGpp synthetases, RelA and RelQ, have been identifiedThe same.RelA mutants differentially express 294 genes, including genes related to metabolism, cell division and growth (Zhang i in., 2016). Both RelA and RelQ are involved in virulence because the expression of many genes associated with virulence factors is under the control of RelA/Q or ppGpp. RelA and RelQ expression is associated with human epithelial cell adhesion and immune evasion, and contributes to virulence in a mouse model (Zhu i sur., 2016). There also seems to be a link between RelA and RelQ with the DNA-binding repressor protein CodY. The additional deletion of CodY in RelA/Q deficient mutants significantly reduces both adherence and survival in whole blood, although this mutant produces a much thicker capsule. The virulence in the mouse model was also reduced, and it has been suggested that many virulence factors influenced by RelA/Q may also be co-regulated by CodY, suggesting a link between these global regulators (Zhu i sur., 2019).

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Enzymology and molecular genetics of biosynthetic enzymes for (1,3)-β-glucans

Vilma A. Stanisich, Bruce A. Stone, wChemistry, biochemistry and biology of 1-3 beta-glucans and related polysaccharides, 2009 (encyclopedic entry).

B.2.4. The relA gene encoding the (p)ppGpp alarm

Another well-known global regulatory system is the stringent response that allows microorganisms to adapt to suboptimal growth conditions (Chatterji i Ojha, 2001). The reaction is mediated by synthesisguanosine pentaphosphateand guanosine tetraphosphate, collectively called (p)ppGpp, which act as alarm signals to initiate an intense stress response and coordinate the entry of the bacterial cell into the stationary phase. atAgrobacterium,The bifunctional enzyme synthetase and hydrolase (p)ppGpp is involved in the production of (p)ppGpp, which has been experimentally investigatedA. tumefaciensA6, where, as expected, the gene encoding (relA) is transcribed only during the stationary growth phase (Zhang i in., 2004). The corresponding gene in LTU50 with which it is 90% identicalrelAA6and 96% identity withrelAC58, was discovered by random Tn mutagenesis, as a defect resulted in curdlan deficiency (Taner i on., 2008). The colony morphology of the mutant on aniline blue agar was characterized by separation of the bacteria into a white colony line that was stable and a light blue colony line that was unstable and maintained both the white and light blue forms after subculturing. Consistent with the staining reaction, both lines produced little recoverable curdlan (6% vs. 2% for light blue and white lines, respectively).

In complementation studies, the mutant restored curdlan production when the clone was reintroducedrelAgene, confirming that the defect inrelAis responsible for the curdlan-deficient phenotype and not for the polarity of downstream genes that are transcribed in the same direction asrelA.ParticipationrelAin polymer production is consistent with the formation of curdlate as a secondary metabolite after cell growth is complete. Use of a constitutive expressionrelAthe complementation study also found that low expression of the gene resulted in colonies that were evenly stained with aniline blue, while increased expression of PgumilakaThe vector plasmid promoter restored curdlan production in some colonies (about 50% stained dark blue) but not in others (which stained light blue). This heterogeneity likely reflects a significant readjustment of the complex and finely tuned cell physiology to unnaturally elevated levels of a key global regulator. Not surprisingly, RelA plays multiple roles in a variety of bacteria, including control of biofilm formation, cell division, and long-term viability (Braeken in sur., 2006), appeared in pleiotropic sequencesrelAmutation in LTU50. In addition to reducing curdlan production, the mutant showed a reduced growth rate with minimal amounts of saltThe medium formed abnormally large cell clumps and produced a brown colored metabolite after prolonged incubation. Also cells fromrelAThe mutants were elongated compared to the LTU50 mutants (~3.6 Pm vs. 2.5 Pm). All these characteristics were restored by feeding the wild typerelAgenes, with the exception of flocculation, which remained at a reduced level in the complemented strain (Taner i on., 2008).

In conclusion, a relatively large number of genes have been shown to influence curdlan production, and others undoubtedly remain to be discovered. Studies to optimize curdlan yield in batch and commercial cultures have shown that curdlan production occurs in the post-stationary phase of growth and depends on many factors, including C and N sources, phosphate, sulfate and cationic composition of the culture medium, as well as pH and degree of permeability substrate (Lee, 2002 (monograph).;McIntosh i sur., 2005). It is likely that the RelA-mediated stress response initiates a cascade of events leading to curdlan production. However, the initiating event and entry into the stationary phase are not sufficient to initiate curdlan production as this only occurs in a chemically defined medium when the N source is depleted and not at all in a nutrient-rich medium. The involvement of NtrBC and NtrYX as activators in the cascade is consistent with the observed relationship between curdlan production and nitrogen supply, as well as the role of the Ntr protein as a sensor of nitrogen deficiency. CrdR may therefore intervene at an even later stage in the cascadefor CPlasmid carrying mutantscrdRThe gene may produce some curdlan on aniline blue agar (Aračić, 2009. (encyclopedic entry).). The target genes of each activator are unknown, and it seems unlikely that NtrC will directly activate any of themcrdRLubcrdASCbecause the areas above these locations contain no visible σ54-similar promoter consensus sequence (Dombrecht et al., 2002 (encyclopedia entry).).

Curdlan production is also strain specific and the required genes appear to be permanently suppressed in many wild strainsAgrobacteriumtribes. Such strains typically produce succinoglycan, an acidic heteropolysaccharide, and produce no or very little curdlan (Dr Nakanishi, 1976).A. tumefaciensAn example is the C58 strain: it is a producer of succinoglycan (Changelosi and sur., 1987) and although it has homologscrdASCGene (and others described above) produce little curdlan. On the other hand, mutants spontaneously producing curdlan, derived from wild-type strains (e.g. LTU50 line) lose the ability to produce succinoglycan (Hisamatsu i dr, 1977), indicating a negative correlation in the production of these polysaccharides. The production and regulation of succinoglycan is poorly understoodAgrobacterium(Ard i sur., 1991;Changelosi and sur., 1987;Tiburtius and Dr., 1996), but are well documented inS. melodywhere the succinoglycan and galactoglucan production pathways are negatively co-regulated (Becker i Puhler, 1998). Hence the superficially similar regulatory interaction between the succinoglycan and curdlan production pathwaysThe replacement of the latter may explain why curdlan production has been overlooked as a feature of agrobacterial biology and raises questions about its role (seeChapter 4.1).

(Video) Stringent response : pppGpp, ppGpp, RelA, Stringent factor

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severe reaction

M. Cashel, K. Potrykus, wBrenner's Encyclopedia of Genetics (Second Edition), 2001 (encyclopedic entry).

the (p)ppGpp cycle

(p) ppGpp metabolic cycle shown inillustration 1is useless because it involves adding pyrophosphate to GDP or GTP and removing pyrophosphate from ppGpp or pppGpp. The cycle is also very fast with a half-life of 20S. The synthetic reaction is catalyzed by a specific domain in the N-terminal part of RelA/RSH and is common to RelP/Q homologues. There is no evidence that small independent RelP/Q synthetases require ribosome binding for this reaction. The regulation of RelP/Q as well as the activity and role of the genes encoding it are currently the subject of intensive research. GppA and Ppx are two transforming gene productsguanosine pentaphosphate(pppGpp) to tetraphosphate (ppGpp). Both enzymes are pppGpp gamma phosphatases that cannot hydrolyze GTP. Overexpression of each protein changes the pppGpp/ppGpp ratio in favor of ppGpp, while only ppGpp is removedgppAchanges these proportions in favor of pppGpp. Ppx is responsible for the turnover of polyphosphates. However, Ppx hydrolysis of polyphosphate is inhibited by high concentrations of pppGpp that compete with the polyphosphate substrate; Physiologically, this response plays a role in adapting to growth transitions between rich and poor media. It is generally accepted that inE colippGpp and pppGpp have similar implications for their regulatory purposes. However, evidence fromgppAMutants and artificial ratio manipulation show that ppGpp is a more potent growth inhibitor than pppGpp. In the wild typeE colicells, levelsE colippGpp exceeds pppGpp during a stringent response. on the other hand inBacillus subtilisThe ratios are reversed, with higher pppGpp values. In this organism, (p)ppGpp inhibits DNA synthesis at the level of DnaG (primase), but pppGpp is more potent than ppGpp. It seems that during an acute response, the most abundant (p)ppGpp pair may be the most potent growth inhibitor. However, the effect of manipulating the (p)ppGpp ratios on the growth of this bacterium was not reported.

Guanosine pentaphosphate - review (1)

(Video) (p)ppGpp Synthetase Purification and In Vitro Activity Assay | Protocol Preview

illustration 1. Top panel: drawing of the generalized domains of the hydrolase synthetase enzyme (p)ppGpp. Full-length proteins are divided into catalytic and regulatory halves, called the N-terminal domain (NTD) and C-terminal domain (CTD), respectively. The catalytic half consists of separate hydrolase and synthetase domains, which may also exist as separate enzymes, such as Mesh2 hydrolase or small RelP/RelQ synthetase. The regulatory portion has a subdomain called TGS that initiates regulation in response to binding of the acyl carrier protein. The CTD also contains the conserved ACT domain whose regulatory functions are less well defined. RelA protein zE coliit has evolved with point mutations that abolish the hydrolase activity, leaving a synthetase that is activated to cover the aminoacyl-tRNA on the ribosomes. SpoT protein zE coliit has a strong hydrolase and a weak synthetase. The basic domain pattern of the nearly ubiquitous RSH enzymes is similarE coli. Bottom panel: Metabolism for the synthesis and degradation of (p)ppGpp is shownE coli. The synthesis of (p)ppGpp by RelA, SpoT or RSH synthetase occurs by transferring pyrophosphate from ATP to the 3'-hydroxyl group of GTP or GDP. After hydrolysis of (p)ppGpp by SpoT or RSH hydrolase, a 3'-pyrophosphate residue is released to regenerate GDP and GTP substrates. The 5'-gamma phosphate can be removed from pppGpp for conversion to ppGpp by two enzymes, GppA (guanosine pentaphosphate phosphatase) or Ppx (polyphosphate hydrolase).

The hydrolysis reaction performed by SpoT/RSH is located in the N-terminal domain of these proteins (illustration 1). The activity and conformation of this domain is affected by ligand binding to the adjacent synthetase domain and possibly additional interactions originating from the C-terminal domain. The regulation of activity is reciprocal - when one increases, the other decreases. The hydrolysis reaction itself requires Mn2+and is specific for the removal of 3'-pyrophosphate from ppGpp and pppGpp with no known other substrates. The TGS domain is largely conserved in RSH enzymes; For SpoT, it has been identified as the binding site for acylated acyl carrier proteins. The SpoT synthetase domain is weakly active compared to most RSH enzymes. The function of the conserved ACT domain is unknown, although mutants in this region, as well as in other parts of the C-terminal domain, may limit dimerization, the physiological consequences of which are unknown.

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Yersinia pestis

Roberta R. Brubakera, wMolecular Medical Microbiology (Second Edition), 2015 (encyclopedic entry).

Global regulation

It is an axiom that the processes of intermediary metabolism between prokaryotes vary greatly depending on the ecological niche occupied by a given organism, while the mechanisms of synthesis and macromolecular regulation remain highly conserved regardless of ecological considerations. This situation largely concerns macromolecular synthesisY. pestisbut not for global regulation.Y. pestisit undergoes traditional DNA repair processes and is stringent (i.e. it produces guanosine tetra- and pentaphosphate after removal of an essential amino acid). As recent genomic analysis shows, plague bacilli develop common key global regulators, including cAMP receptor protein (CRP), leucine regulatory protein (Lrp), DNA double bond transcription regulator PhoP and its sensor protein PhoQ, transcription regulator RovA (MARS family member/ SlyA) and H-NS nucleoid structural protein. However, many of these systems have been significantly redesigned compared to those inE colialso consider recent publicationsY. pestisfrom severe environmental constraints and the need to adapt to unique in vivo signals (although these modifications are sometimes shared with others).Y. pseudotuberkuloza). The classic two-component PhoP/PhoQ regulatory system is required for survivalY. pestisyou Mg2+-deficiency of macrophage phagolysosomes[47]; This effect is partly due to the induction of the magnesium translocating P-type ATPase (MgtA). This is due to the high osmolarity of the mammalian intestine (≥300 mOsm).E colito increase OmpC porin (small pore size) and decrease OmpF (pore size), while in soil and water the opposite situation occurs where osmolarity is significantly reduced. In this case, CRP-regulated phosphorylated OmpR gradually binds to the upstream regionsompFIompCas a function of osmolarity until saturation followed by transcriptionompFstops due to the formation of a circular loop. However, inY. pestisCRP directly recognizes the promoterompCIompFbut not its own structural gene and therefore has no effect onompR [48]. The PhoP/PhoQ system normally controls a number of other functions, including the transcription of the RstA/RstB binary regulatory system (controlling acid-fast genes), its own autoregulator (MgrB), initiator of hemin synthesis (Heml), and surface lipoproteins (e.g., B., SlyB), which are also reduced in Mg2+Surplus. TheThe regulated PhoP and RovA are integratedY. pestisfound that PhoP downregulates RovA by recognizing its promoter, while RovA directly activates the transcription of its own structural gene[49]. In addition, PhoPY. pestisis capable of both positive and negative autoregulation and acts as an activator of adenylyl cyclase transcriptioncrpThis shows that the PhoP and CRP regulators of this organism have evolved into a single regulatory cascade[50].

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(Video) Crystal structure of E. coli RNA polymerase and DksA/ppGpp complex

Important 3′–5′ exoribonucleases in the metabolism of coding and non-coding RNA

Ricardo F. dos Santos, ... José M. Andrade, wAdvances in Molecular Biology and Translational Sciences, 2018 (encyclopedic entry).

2.3 PNPaze structure

Pure PNPase was isolatedE colistrong subunit of the homotrimer with a mass of 78 kDa.84X-ray crystal structuresE coli,Streptomyces antibioticIC is increasingPNPase reveals the organization of a homotrimeric subunit with ring architecture (Thread. 3).11,51,85,86Each monomer has an assembly of five domains: at the N-terminus, the two RNase PH domains (first and second core domains) are connected by an α-helical domain87; At the C-terminus are two RNA binding domains called KH and S188(Thread. 3). In the quaternary structure, the KH and S1 domains are on one side of the trimer, while the active site (RNase PH domain) is on the opposite side. The three subunits associate through the trimerization sites of the core domains and form a central channel where catalysis takes place. The presence of conserved basic residues in the gate region as well as adequate channel constriction are critical for RNA capture for process degradation.85Two constriction points in the channel were identified, and the structure of the PNPase in complex with RNA clearly indicates that the path followed by the RNA molecule is along the central pore towards the active site.11,51,85The dynamic translocation of RNA by the enzyme depends on the conformational changes that occur in the opening of the central channel and adjacent regions.51Kinetic studies have shown that the presence of distinct and different RNA binding sites is partly responsible for the processivity of the PNPase. The trimeric channel probably contributes to the processivity and regulation of PNPase activity through RNA structural elements.11

The first core RNase PH domain has a conserved FFRR loop that interacts with the RNA about 20 Å from the putative catalytic site in the second core.89TwoE coliPNPase mutants in the FFRR loop (Arg79Ala and Arg80Ala) showed a strong increasekMfor ADP/Pi binding. In addition, it has been suggested that the first primary domain is involvedguanosine pentaphosphate(pppGpp) synthetase activityS.antibioticPNPase, absent in most PNPases.11The second core domain of RNase PH binds tungstate, a phosphate analog, suggesting that a catalytic center is located here. This region may also have been separately adapted as a second active site in PNPases overall.11Most of the conserved residues are concentrated in the second core domain (which contains the putative catalytic site) and a small portion of the first core domain. Few of them are in the KH or S1 RNA-binding domains. Mutations in the amino acids around the tungstate binding site abolish or significantly reduce all catalytic activities of the enzyme, suggesting that these mutations affect the catalytic site directly.90 E coliPNPase crystals obtained in the presence of Mn2+showed that the cofactor is coordinated by the conserved residues Asp486, Asp492 and Lys494.51In addition, the Asp492 mutation eliminates both phosphorolytic and polymeric activity.90

The α-helical domains connecting the first and second core domains are involved in the catalytic activityE coliPNPase,91although they are the least maintained domains.25,90uE coliPNPase mutating adjacent α-helical domain residues appears to affect catalytic activity.91AnalyzeS.antibioticThe structure revealed that the α1 helix faces the putative phosphate binding site and thus may be part of the catalytic center.11,91These results were combined with studies of spinach chloroplasts and human PNPases92,93suggest a catalytic siteE coliThe PNPase likely consists of structural elements in the first and second core domains (Thread. 3).

On the other hand, RNA binding domains have a limited effect on phosphorolysis because PNPase mutants lacking either domain are catalytically active. Electrophoretic RNA mobility shift assays showed that both KH and S1 domains are required for proper binding94and for PNPase autoregulation.95Interestingly, the PNPase truncated in these two domains can still bind RNA, albeit with lower affinity, confirming that the catalytic core has intrinsic RNA-binding activity. In addition, the S1 and KH domains are required to release the substrate from the catalytic site.96To explain this, a two-step model has been proposed based on the indirect facilitation of PNPase activity by the KH and S1 domains, allowing substrate binding and product release. The model assumes that there are two RNA-binding surfaces on each PNPase monomer: one in the catalytic core domain and the other formed by the KH and S1 domains. First, the ssRNA molecules are thought to weakly interact with one of the KH-S1 tandem domains. This bound ssRNA then interacts strongly with the catalytic site where it undergoes phosphorolysis until the stem loop is formed and the enzyme stops as the substrate remains bound to the binding surface of the RNA core. Finally, another molecule could bind to another empty KH-S1 tandem domain, migrate to the nuclear RNA binding site and allow the locked molecule to move. Therefore, the truncated ΔKH-S1 proteins are much less efficient in releasing products after catalysis.96

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METABOLISM | lipid metabolism

R.Sandhira, wEncyclopedia of Food Microbiology (Second Edition), 2014 (encyclopedic entry).

(Video) Microtiter Dish Radiolabeling: Multiple Measurements-E coli (p)ppGpp l Protocol Preview

fatty acid biosynthesis

Most natural fatty acids have an even number of carbon atoms. Fatty acid biosynthesis occurs through the sequential addition of 2-carbon units derived from acetyl-CoA and occurs in the cytoplasm of bacteria and fungi (Figure 16). The first step in fatty acid synthesis is the carboxylation of acetyl-CoA to malonyl-CoA, a key intermediate in fatty acid synthesis, catalyzed by the enzyme acetyl-CoA carboxylase. The formation of malonyl-CoA requires ATP as well as biotin and CO2as a cofactor. The need for biotin in this reaction is one of the reasons why many organisms require trace amounts of biotin as a growth factor. INEscherichia coli,Acetyl-CoA carboxylase consists of three separate components. One protein contains biotin with a molecular weight of 22.5 kDa and biotin carboxyl transfer protein (BCCP). The second component with a molecular weight of 102 kDa consists of two subunits and catalyzes the biotin carboxylase reaction. The last component (130 kDa) contains two pairs of non-identical 30 and 35 kDa subunits and catalyzes the carboxyltransferase reaction. Evidence from various studies indicates that yeast and fungal acetyl-CoA carboxylase consists of one multifunctional protein. The molecular weight of these proteins ranges from 189-230 kDa in yeast.S. cerevisiaeICandida lipolytic.The yeast enzyme can be produced in a citrate-activated form, but this activation does not involve polymerization of the enzyme as in higher eukaryotes. However, bacterial acetyl-CoA carboxylase is not regulated by citrate nor under the control of phosphorylation; Instead, it is regulated by the nucleosides 3'-diphosphate, guanosine 5'-diphosphate (ppGpp) and 3'-diphosphate, guanosine 5'-triphosphate (pppGpp), which reduce enzyme activity by inhibiting the carboxyl transferase. Unique to bacteria, these guanosine nucleosides are formed by the transfer of phosphoribosyl from ATP to GDP or GTP on the ribosome in response to amino acid starvation or when other conditions of reduced growth rate render the ribosome "inactive".

Guanosine pentaphosphate - review (2)

Figure 16. fatty acid biosynthesis. Fatty acid biosynthesis involves the addition of 2 carbon atoms to an acyl carrier protein (ACP).

Malonyl-CoA generated by acetyl-CoA carboxylase is the source of all the carbon atoms in the fatty acyl chain. The group of enzymes that catalyze fatty acid synthesis are collectively known as fatty acid synthase (FAS) and include seven distinct enzyme activities. First, the primer molecule is transferred from acetyl-CoA to the -SH group of the acyl carrier protein (ACP) on the FAS, with the help of the transacylase enzyme, and then malonyl-CoA is transferred to the 4'-phosphopantotheine of the ACP, which catalyzes the release of CoA to become the enzyme malonyl transacylase. The acetyl group attacks the methylene group of the malonyl residue, catalyzed by β-ketoacyl synthase and forms acetoacetyl-ACP with release of CO2. This releases the -SH group of ACP that was occupied by the acetyl group. Acetoacetyl-ACP is then reduced, dehydrated and reduced again to form butyryl-ACP catalyzed by β-ketoacyl reductase, hydratase and enoyl reductase. Reductases require NADPH as a cofactor. In addition, elongation occurs through malonyl-CoA, which adds more 2-carbon units to the growing acyl chain, and the cycle repeats, finally giving C16fatty acid (palmitic acid). The resulting palmitic acid is released by the seventh enzyme thioesterase. The general reaction of palmitic acid is as follows:

8 Acetylo-CoA + 7 ATP +14 NADPH →

palmitic acid + 14 NADP++ 8 CoA+6 pcs2O + 7 PI

Fatty acid synthases can be broadly divided into type I and type II enzymes. Type I synthases are multifunctional proteins in which the proteins catalyze individual partial reactions in separate domains and the protein acyl carrier is covalently bound to the protein. This type includes synthases from higher bacteria (Mycobacterium smegmatisICornybacteriumspp.) and yeast (S. cerevisiae). Type I synthases are proteins with a characteristic high molecular weight (0.4 × 10).6–2,5 × 106), which consists of two or more large multifunctional polypeptide chains (molecular weight 1.8 × 10).5–2,7 × 105). Typ IM. smegmatykis unusual in several respects; The two reductases have different specificities for reduced pyridine nucleotides, the β-ketoacyl-ACP reductase requiring NADPH and the enoyl-ACP reductase requiring NADH (other type I enzymes use only NADPH). In animals, the two chains are generally assumed to be identical. Recent genetic analyzes of yeast fatty acid synthase mutants have revealed that there are two unrelated polycistronic genes, designatedfas1 andfas2.Thefas1 gene encodes the enzymes acetyltransferase, malonyl (palmitoyl) transacylase, dehydratase and enoyl reductasefas2 encodes the binding region for phospho-pantothene and the enzymes β-ketoacyl synthase and reductase. The yeast synthase is probably A6B6A complex of two different multifunctional proteins (A and B). Type I yeast inhibits palmitoyl-CoA and this zAspergillus fumigatusinhibit malonyl-CoA.

Type II synthases contain enzymes that can be separated, purified, and studied separately, and are present in most lower bacteria (E coli) and the acyl carrier protein are easily separated from the enzyme. The type II synthase is the best studiedE coliseven proteins were isolated. It is assumed that in the cell, individual enzymes combine into a loosely bound multienzyme complex. The site of association may be the cell membrane, because inE coli,ACP is located in the membrane. In these reactions, substrates bind to ACP. The type II enzyme synthesizes both saturated and unsaturated fatty acids. This is due to the presence of releasing β-hydroxydecanoyl-ACP-β,γ-dehydrasecis-3-decenoyl-ACP (precursor of unsaturated fatty acids).trans-2-decenoyl-ACP, which is converted into a saturated fatty acid.

In yeast and fungi, the saturated fatty acids are palmitic acid (C16) and stearic acid (C18) serve as precursors to the monounsaturated fatty acids palmitoleic acid and oleic acid. The double bond is formed by the action of the fatty acyl-CoA oxygenase enzyme in an oxidation reaction. In the reaction, NADPH is oxidized to NADP+.

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(Video) Phosphotransferase-dependent accumulation of (p)ppGpp in response to glutamine deprivation


What does guanosine pentaphosphate do? ›

Accumulation of guanosine pentaphosphate (ppGpp) commonly serves as an “alarmone,” a stress response signal, in many bacterial species (Irving, Choudhury, & Corrigan, 2020). The production of ppGpp by RelA is triggered as a stress response, such as amino acid or carbon starvation (Magnusson, Farewell, & Nystrom, 2005).

What is the stringent response of ppGpp? ›

The stringent response is signaled by the alarmone (p)ppGpp, and modulates transcription of up to 1/3 of all genes in the cell. This in turn causes the cell to divert resources away from growth and division and toward amino acid synthesis in order to promote survival until nutrient conditions improve.

How does ppGpp work? ›

In E. coli, a primary target for ppGpp is RNA polymerase (RNAP). Direct binding of ppGpp to sites on RNAP, aided by the protein cofactor DksA, downregulates ribosomal RNA and ribosomal protein synthesis and upregulates transcription of genes for amino acid biogenesis.

How is ppGpp produced? ›

(p)ppGpp is created via pppGpp synthase, also known as RelA, and is converted from pppGpp to ppGpp via pppGpp phosphohydrolase.

Is ppGpp a second messenger? ›

(p)ppGpp (collective for ppGpp and pppGpp) is a nucleotide based second messenger and a key regulator of stringent stress response in many bacteria. During nutritional starvation (p)ppGpp initiates the switch from bacterial growth into survival mode.

What triggers a stringent response? ›

The stringent response (SR) is a broadly conserved bacterial stress response that controls adaptation to nutrient deprivation, and is activated by a number of different starvation and stress signals.

What does ppGpp bind to? ›

Abstract. The second messenger nucleotide ppGpp dramatically alters gene expression in bacteria to adjust cellular metabolism to nutrient availability. ppGpp binds to two sites on RNA polymerase (RNAP) in Escherichia coli, but it has also been reported to bind to many other proteins.

Is ppGpp an alarmone? ›

ppGpp accumulates in bacterial cells upon exposure to various stresses and the accumulated ppGpp functions as an alarmone that can alter transcription3,4,5,6, translation7,8, and certain enzymatic activities6,9,10 to overcome a stress3.

Where does ppGpp bind? ›

coli RNA polymerase holoenzyme does not involve the σ70 factor. ppGpp binds in a small, positively-charged pocket (Figure 1C) that lies on the edge of the interface between the β′ and ω subunits.

Is ppGpp a cell size regulator? ›

Our findings suggest that ppGpp serves as a key regulator that coordi- nates cell size and growth control. Bacterial cell size and growth coordination Many bacterial species are known to display faster average growth and larger cell sizes in nutrient-rich media—a correlation that is also referred to as the growth law.

Is ppGpp a protein? ›

“Short” RSH proteins consisting only of a (p)ppGpp synthetase or hydrolase domain constitute the class of small alarmone synthetases (SAS) and hydrolases (SAH), respectively (Atkinson et al., 2011).

Is ppGpp a nucleotide? ›

(p)ppGpp is a nucleotide messenger universally produced in bacteria following nutrient starvation. In E. coli, ppGpp inhibits purine-nucleotide synthesis by targeting several different enzymes, but the physiological significance of their inhibition is unknown.

What is the name of ppGpp? ›

Guanosine 5'-diphosphate 2'(3')-diphosphate. A guanine nucleotide containing four phosphate groups.

What is the function of the methylated guanosine cap on the RNA? ›

The 7-methylguanosine cap is essential for mRNA translation and cell viability from yeast to mammals. It also has a role in transcription elongation, mRNA stability and degradation, and mediates other RNA processing events, including splicing, poly(A) tail addition and nuclear export.

What is guanosine monophosphate in food? ›

Food additive

Guanosine monophosphate is known as E number reference E626. In the form of its salts, such as disodium guanylate (E627), dipotassium guanylate (E628) and calcium guanylate (E629), are food additives used as flavor enhancers to provide the umami taste.

What is guanosine nucleotide? ›

Guanosine is a purine nucleoside in which guanine is attached to ribofuranose via a beta-N(9)-glycosidic bond. It has a role as a fundamental metabolite. It is a purines D-ribonucleoside and a member of guanosines. It is functionally related to a guanine.

What would happen if the 5 methyl guanosine cap was not added to an mRNA? ›

25. What would happen if the 5' methyl guanosine was not added to an mRNA? The transcript would degrade when the mRNA moves out of the nucleus to the cytoplasm. The mRNA molecule would stabilize and start the process of translation within the nucleus of the cell.

Why is RNA methylation important? ›

This study confirmed the important role of RNA methylation in promoting UV resistance of cells, and found a new pathway in which METTL3, m6A RNA and “Pol k” play an important role in the early stage of UV induced DDR response, and RNA methylation is crucial for the recruitment of “Pol k” to the damage site [51].

What is GTP cap in RNA processing? ›

The capping process replaces the triphosphate group with another structure called the "cap". The cap is added by the enzyme guanyl transferase. This enzyme catalyzes the reaction between the 5' end of the RNA transcript and a guanine triphosphate (GTP) molecule.

What foods have guanosine? ›

Guanosine is found in many foods, some of which are elderberry, malus (crab apple), acerola, and arrowhead.

Is guanosine naturally found in the body? ›

Adenosine and guanosine are endogenous purines and exist in the body in the free form, attached to ribose or deoxyribose (as nucleosides), and as mono-, bi- or triphosphorylated nucleotides.

What are the uses of guanosine? ›

These forms play important roles in various biochemical processes such as synthesis of nucleic acids and proteins, photosynthesis, muscle contraction, and intracellular signal transduction (cGMP).

Is guanosine RNA or DNA? ›

Guanine (/ˈɡwɑːnɪn/) (symbol G or Gua) is one of the four main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, and thymine (uracil in RNA). In DNA, guanine is paired with cytosine. The guanine nucleoside is called guanosine.

What is an example of guanosine? ›

When a phosphate group is covalently attached to the sugar, it forms a nucleotide. An example of a nucleotide wherein three phosphate groups are attached to guanosine is guanosine triphosphate (GTP), one of the building blocks of RNA synthesis.

Why is guanine so important? ›

What is the function of guanine? Guanine functions as a building block of DNA to encode information. It is also utilized for energy and in many different G proteins.


1. CryoEM structures of the rRNA promoter complex with DksA/ppGpp
(Murakami Lab, Penn State)
2. Alternative pathways for open promoter complex formation
(Murakami Lab, Penn State)
3. Assembly of DksA and ppGpp to RNAP triggers conformational changes in RNAP and DksA
(Murakami Lab, Penn State)
4. Sharon Long (Stanford) Part 2: Function and regulation of Sinorhizobium nodulation genes
5. T7 phage factor required for managing RpoS in Escherichia coli
6. 千萬別錯過這個菜,它是「腰痛」的救星,每周吃2次,腰不痛,腿不軟,血糖血壓平穩了,效果太好了


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