Osmoprotectant-dependent expression of plcH, encoding the hemolytic phospholipase C, is subject to novel catabolite repression control in Pseudomonas aeruginosa PAO1

Sage, Andrew; Vasil, Michael L.

doi:10.1128/jb.179.15.4874-4881.1997

Cited by 34 publications

(39 citation statements)

References 41 publications

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“…As far as we are aware, this is the first report suggesting that the target specificity of a CRP homolog may be modulated by binding more than one type of cNMP. In P. aeruginosa, intracellular levels of cAMP do not correlate with carbon source availability (36) and, unlike CRP, Vfr does not appear to be required for catabolite repression (40,48). Despite this, Vfr can substitute for CRP in a cAMPdependent fashion (56), indicating that Vfr can be activated by cAMP.…”

Section: Discussionmentioning

confidence: 99%

Differential Regulation of Twitching Motility and Elastase Production by Vfr in Pseudomonas aeruginosa

Beatson

Whitchurch²,

Sargent³

et al. 2002

J Bacteriol

173

141

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Vfr, a homolog of Escherichia coli cyclic AMP (cAMP) receptor protein, has been shown to regulate quorum sensing, exotoxin A production, and regA transcription in Pseudomonas aeruginosa. We identified a twitching motility-defective mutant that carries a transposon insertion in vfr and confirmed that vfr is required for twitching motility by construction of an independent allelic deletion-replacement mutant of vfr that exhibited the same phenotype, as well as by the restoration of normal twitching motility by complementation of these mutants with wild-type vfr. Vfr-null mutants exhibited severely reduced twitching motility with barely detectable levels of type IV pili, as well as loss of elastase production and altered pyocyanin production. We also identified reduced-twitching variants of quorum-sensing mutants (PAK lasI::Tc) with a spontaneous deletion in vfr (S. A. Beatson, C. B. Whitchurch, A. B. T. Semmler, and J. S. Mattick, J. Bacteriol., 184:3598-3604, 2002), the net result of which was the loss of five residues (EQERS) from the putative cAMP-binding pocket of Vfr. This allele (Vfr⌬EQERS) was capable of restoring elastase and pyocyanin production to wild-type levels in vfr-null mutants but not their defects in twitching motility. Furthermore, structural analysis of Vfr and Vfr⌬EQERS in relation to E. coli CRP suggests that Vfr is capable of binding both cAMP and cyclic GMP whereas Vfr⌬EQERS is only capable of responding to cAMP. We suggest that Vfr controls twitching motility and quorum sensing via independent pathways in response to these different signals, bound by the same cyclic nucleotide monophosphate-binding pocket.

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Section: Discussionmentioning

confidence: 99%

Differential Regulation of Twitching Motility and Elastase Production by Vfr in Pseudomonas aeruginosa

Beatson

Whitchurch²,

Sargent³

et al. 2002

J Bacteriol

173

141

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“…In addition, GB can induce expression of known and predicted virulence-related proteins (23,30), which may impact P. aeruginosa survival and/or pathogenesis in the host. By controlling the catabolism of GB, GbdR may also play an important role during P. aeruginosa interactions with eukaryotes.…”

Section: Discussionmentioning

confidence: 99%

“…Alternatively, GB can be derived from choline or carnitine (4,5,12,15,20,36). Choline and carnitine can be found in many eukaryote-associated environments, and bacteria, including P. aeruginosa, can use phospholipases and choline phosphatases to release choline from phosphatidylcholine (30,38). In P. aeruginosa, choline is oxidized to GB by a two-step process catalyzed by BetA and BetB (29,36), while carnitine is predicted to be reduced and deacetylated by uncharacterized enzymes, ultimately yielding GB (16).…”

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confidence: 99%

Identification of Two Gene Clusters and a Transcriptional Regulator Required for Pseudomonas aeruginosa Glycine Betaine Catabolism

Wargo¹,

Szwergold

Hogan³

2008

J Bacteriol

114

180

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Glycine betaine (GB), which occurs freely in the environment and is an intermediate in the catabolism of choline and carnitine, can serve as a sole source of carbon or nitrogen in Pseudomonas aeruginosa. Twelve mutants defective in growth on GB as the sole carbon source were identified through a genetic screen of a nonredundant PA14 transposon mutant library. Further growth experiments showed that strains with mutations in two genes, gbcA (PA5410) and gbcB (PA5411), were capable of growth on dimethylglycine (DMG), a catabolic product of GB, but not on GB itself. Subsequent nuclear magnetic resonance (NMR) experiments with 1,2-13 C-labeled choline indicated that these genes are necessary for conversion of GB to DMG. Similar experiments showed that strains with mutations in the dgcAB (PA5398-PA5399) genes, which exhibit homology to genes that encode other enzymes with demethylase activity, are required for the conversion of DMG to sarcosine. Mutant analyses and 13 C NMR studies also confirmed that the soxBDAG genes, predicted to encode a sarcosine oxidase, are required for sarcosine catabolism. Our screen also identified a predicted AraC family transcriptional regulator, encoded by gbdR (PA5380), that is required for growth on GB and DMG and for the induction of gbcA, gbcB, and dgcAB in response to GB or DMG. Mutants defective in the previously described gbt gene (PA3082) grew on GB with kinetics similar to those of the wild type in both the PAO1 and PA14 strain backgrounds. These studies provided important insight into both the mechanism and the regulation of the catabolism of GB in P. aeruginosa.A number of microbes, including Pseudomonas aeruginosa, can utilize glycine betaine (GB) as a sole carbon, nitrogen, and energy source (17,35,41). GB, an important osmoprotectant for many bacteria (6), is available to organisms in a variety of environments (5,14,34,41). Free GB can be released by roots (9), microbes (14, 15), or decaying animal (20) and plant (10) matter. Alternatively, GB can be derived from choline or carnitine (4,5,12,15,20,36). Choline and carnitine can be found in many eukaryote-associated environments, and bacteria, including P. aeruginosa, can use phospholipases and choline phosphatases to release choline from phosphatidylcholine (30, 38). In P. aeruginosa, choline is oxidized to GB by a two-step process catalyzed by BetA and BetB (29,36), while carnitine is predicted to be reduced and deacetylated by uncharacterized enzymes, ultimately yielding GB (16).The aerobic catabolism of GB in bacteria is best understood in Sinohizobium (35), Corynebacterium (8, 37), and Arthrobacter species (24). The data from these studies suggest that GB catabolism occurs via serial demethylation that forms dimethylglycine (DMG), then sarcosine (also called monomethylglycine), and finally glycine (Fig. 1). Thin-layer chromatographic analyses indicated that in P. aeruginosa DMG and sarcosine are also intermediates formed during GB catabolism (11). Furthermore, in the same study, a proteomics analysis of P. aeruginosa cul...

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“…Leukotoxin production in Actinobacillus actinomycetemcomitans is repressed by glucose or fructose (35). A novel catabolite repression system controls expression of hemolytic phospholipase C of Pseudomonas aeruginosa (45). In Staphylococcus aureus, glycerol and maltose repress enterotoxin A synthesis through the phosphoenolpyruvate phosphotransferase system (50).…”

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confidence: 99%

CcpC-Dependent Regulation ofcitBand lmo0847 inListeria monocytogenes

2006

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In Bacillus subtilis, the catabolite control protein C (CcpC) plays a critical role in regulating the genes encoding the enzymes of the tricarboxylic acid branch of the Krebs citric acid cycle. A gene encoding a potential CcpC homolog and two potential target genes were identified in the Listeria monocytogenes genome. In vitro gel mobility shift assays and DNase I footprinting experiments showed that L. monocytogenes CcpC (CcpC Lm ) interacts with the promoter regions of citB Lm (the gene that is likely to encode aconitase) and lmo0847 (encoding a possible glutamine transporter) and that citrate is a specific inhibitor of this interaction. To study in vivo promoter activity, a new lacZ reporter system was developed. This system allows stable integration into the chromosome of a promoter region transcriptionally fused to a promoterless lacZ gene at a nonessential, ectopic locus. Analysis of strains carrying a citB Lm -lacZ or lmo0847-lacZ fusion revealed that CcpC Lm represses citB Lm and lmo0847 in media containing an excess of glucose and glutamine. In addition, regulation of citB Lm expression in rich medium was growth phase dependent; during exponential growth phase, expression was very low even in the absence of CcpC Lm , but a higher level of citB Lm expression was induced in stationary phase, suggesting the involvement of another, as yet unidentified regulatory factor.Listeria monocytogenes is a gram-positive, facultative, intracellular pathogen responsible for listeriosis, a serious infection with a mortality rate of up to 30%, mainly among pregnant women, their fetuses, and immunocompromised persons. Listeriosis is characterized by gastroenteritis and fetoplacental and central nervous system infection, resulting in spontaneous abortion, neonatal death, septicemia, and meningitis (58). L. monocytogenes is widespread in nature and is predominantly transferred to humans by ingestion of contaminated foods (13). The bacterium can invade and multiply inside a wide range of phagocytic and nonphagocytic mammalian cells and has served as an important model system for studying the mechanisms of both intracellular parasitism and host cell biology (7,40,41).A great deal of effort has been invested in isolating L. monocytogenes virulence genes and understanding mechanisms of pathogenesis (reviewed in reference 58). However, our knowledge of the basic physiology of this important pathogen is very limited, making it difficult to gain a comprehensive understanding of its pathogenesis. There has been increasing evidence that regulation of carbon metabolic pathways plays a critical role in the virulence of pathogenic bacteria. Regulation of the Salmonella enterica virulence operon spv is controlled by cyclic AMP-cyclic AMP receptor protein complex, the major catabolite regulator, as well as by the positive regulator SpvR (38). Similarly, Escherichia coli STb enterotoxin production is repressed by glucose, and repression is relieved by addition of cyclic AMP (4). Leukotoxin production in Actinobacillus actinomycetemcomitan...

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Osmoprotectant-dependent expression of plcH, encoding the hemolytic phospholipase C, is subject to novel catabolite repression control in Pseudomonas aeruginosa PAO1

Cited by 34 publications

References 41 publications

Differential Regulation of Twitching Motility and Elastase Production by Vfr in Pseudomonas aeruginosa

Differential Regulation of Twitching Motility and Elastase Production by Vfr in Pseudomonas aeruginosa

Identification of Two Gene Clusters and a Transcriptional Regulator Required for Pseudomonas aeruginosa Glycine Betaine Catabolism

CcpC-Dependent Regulation ofcitBand lmo0847 inListeria monocytogenes

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