Interaction of the Antiactivator FleN with the Transcriptional Activator FleQ Regulates Flagellar Number in
            <i>Pseudomonas aeruginosa</i>

Dasgupta, Nandini; Ramphal, Reuben

doi:10.1128/jb.183.22.6636-6644.2001

Cited by 115 publications

(155 citation statements)

References 28 publications

(34 reference statements)

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“…The expression of regA, lasR and fleQ, other known Vfr targets, was not altered in the rsmA mutant. However, the transcription of regA, lasR and fleQ is also controlled by numerous other regulators (Dasgupta & Ramphal, 2001;Dasgupta et al, 2003;Hunt et al, 2002;Juhas et al, 2005), which could compensate for the drop in vfr levels. To confirm the novel impact of RsmA on Vfr levels, a vfr-lacZ transcriptional fusion (pCUB26) was constructed and analysed in PAO1 and the rsmA mutant (Fig.…”

Section: Resultsmentioning

confidence: 99%

Influence of the regulatory protein RsmA on cellular functions in Pseudomonas aeruginosa PAO1, as revealed by transcriptome analysis

et al. 2006

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RsmA is a posttranscriptional regulatory protein in Pseudomonas aeruginosa that works in tandem with a small non-coding regulatory RNA molecule, RsmB (RsmZ), to regulate the expression of several virulence-related genes, including the N-acyl-homoserine lactone synthase genes lasI and rhlI, and the hydrogen cyanide and rhamnolipid biosynthetic operons. Although these targets of direct RsmA regulation have been identified, the full impact of RsmA on cellular activities is not as yet understood. To address this issue the transcriptome profiles of P. aeruginosa PAO1 and an isogenic rsmA mutant were compared. Loss of RsmA altered the expression of genes involved in a variety of pathways and systems important for virulence, including iron acquisition, biosynthesis of the Pseudomonas quinolone signal (PQS), the formation of multidrug efflux pumps, and motility. Not all of these effects can be explained through the established regulatory roles of RsmA. This study thus provides both a first step towards the identification of further genes under RsmA posttranscriptional control in P. aeruginosa and a fuller understanding of the broader impact of RsmA on cellular functions.

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Section: Resultsmentioning

confidence: 99%

Influence of the regulatory protein RsmA on cellular functions in Pseudomonas aeruginosa PAO1, as revealed by transcriptome analysis

et al. 2006

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“…Flagella genes under the control of FleQ, including the fleN gene, are expressed (9). The FleN protein interacts with FleQ bound to flagella gene promoters (7,14) and inhibits FleQ ATPase activity (Fig. 3).…”

Section: Discussionmentioning

confidence: 99%

“…Previously reported data indicate that FleN is a FleQ antiactivator. Flagella gene expression is high in an fleN background (12,14).…”

Section: Flen Exhibits Low Atpase Activity and Inhibits Fleq Atpase Amentioning

confidence: 99%

“…FleN is a putative ATPase containing a deviant Walker A motif (13). FleN and FleQ interact with one another in the presence as well as in the absence of ATP or c-di-GMP, and a FleQ/FleN complex binds to pel, fleSR, and flhA promoter DNA (7,8,14).Transcriptome studies have shown that the expression of most FleQ-controlled flagella genes is down-regulated by 1.5-to 2-fold when intracellular c-di-GMP is high (7,15). To investigate the basis for this effect, we tested the influence of c-di-GMP on FleQ ATPase activity.…”

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confidence: 99%

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Cyclic diguanosine monophosphate represses bacterial flagella synthesis by interacting with the Walker A motif of the enhancer-binding protein FleQ

Baraquet

Harwood

2013

Proc. Natl. Acad. Sci. U.S.A.

164

192

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The transcription factor FleQ is a bacterial AAA+ ATPase enhancerbinding protein that is the master activator of flagella gene expression in the opportunistic bacterial pathogen Pseudomonas aeruginosa. Homologs of FleQ are present in all Pseudomonas species and in many polarly flagellated gamma proteobacteria. Cyclic diguanosine monophosphate (c-di-GMP) is a second messenger that controls the transition between planktonic and biofilm modes of growth in bacteria in response to diverse environmental signals. C-di-GMP binds to FleQ to dampen its activity, causing down-regulation of flagella gene expression. This action is potentiated in the simultaneous presence of another protein, FleN. We explored the effect of c-di-GMP and FleN on the ATPase activity of FleQ and found that a relatively low concentration of c-di-GMP competitively inhibited FleQ ATPase activity, suggesting that c-di-GMP competes with ATP for binding to the Walker A motif of FleQ. Confirming this, a FleQ Walker A motif mutant failed to bind c-di-GMP. FleN, whose gene is regulated by FleQ, also inhibited FleQ ATPase activity, and FleQ ATPase activity was much more inhibited by c-di-GMP in the presence of FleN than in its absence. These results indicate that FleN and c-di-GMP cooperate to inhibit FleQ activity and, by extension, flagella synthesis in P. aeruginosa. The Walker A motif of FleQ is perfectly conserved, opening up the possibility that other AAA+ ATPases may respond to c-di-GMP.an ubiquitous second messenger in bacteria, where it affects the transition between a motile planktonic lifestyle and an adhesive biofilm lifestyle by binding to various effector proteins to modulate enzymatic activity, protein-protein interactions, transcription, and translation (1-6). One of these effector proteins is FleQ (PA1097), an enhancer-binding protein (EBP) transcription factor from the opportunistic pathogen Pseudomonas aeruginosa.FleQ contains an N-terminal FleQ domain, a central AAA+ ATPase domain, and a C-terminal helix-turn-helix DNA-binding domain. It activates expression of biofilm-related genes, including genes for Pel and Psl exopolysaccharide (EPS) in response to binding of c-di-GMP at an unknown site (7,8). EBPs typically act in conjunction with σ 54 -RNA polymerase; however, FleQ regulates EPS gene expression independent of σ 54 , most likely with σ 70 (8, 9).In addition to regulating genes for biofilm formation, FleQ has a second, better-known role as a σ 54 -dependent master regulator of P. aeruginosa flagella gene expression (9, 10). FleQ activates expression of the two-component regulatory genes fleSR, as well as genes for the assembly of the flagella export apparatus and for the initiation of flagella basal body assembly. FleSR controls genes to complete the basal body-hook structure (9, 11).The regulation of both flagella and biofilm genes is also under the control of a second protein, FleN. Mutations in fleN (PA1454) lead to an up-regulation of flagella gene expression and a smalldown-regulation of biofilm genes (7, 12). The expression ...

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The N‐terminal FleQ domain of the Vibrio cholerae flagellar master regulator FlrA plays pivotal structural roles in stabilizing its active state

et al. 2023

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In Vibrio cholerae, the master regulator FlrA controls transcription of downstream flagellar genes in a σ54‐dependent manner. However, the molecular basis of regulation by VcFlrA, which contains a phosphorylation‐deficient N‐terminal FleQ domain, has remained elusive. Our studies on VcFlrA, four of its constructs, and a mutant showed that the AAA+ domain of VcFlrA, with or without the linker ‘L’, remains in ATPase‐deficient monomeric states. By contrast, the FleQ domain plays a pivotal role in promoting higher‐order functional oligomers, providing the required conformation to ‘L’ for ATP/cyclic di‐GMP (c‐di‐GMP) binding. The crystal structure of VcFlrA‐FleQ at 2.0 Å suggests that distinct structural features of VcFlrA‐FleQ presumably assist in inter‐domain packing. VcFlrA at a high concentration forms ATPase‐efficient oligomers when the intracellular c‐di‐GMP level is low. Conversely, excess c‐di‐GMP locks VcFlrA in a non‐functional lower oligomeric state, causing repression of flagellar biosynthesis.

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Interaction of the Antiactivator FleN with the Transcriptional Activator FleQ Regulates Flagellar Number in Pseudomonas aeruginosa

Abstract: Flagellar number in

Cited by 115 publications

References 28 publications

Influence of the regulatory protein RsmA on cellular functions in Pseudomonas aeruginosa PAO1, as revealed by transcriptome analysis

Influence of the regulatory protein RsmA on cellular functions in Pseudomonas aeruginosa PAO1, as revealed by transcriptome analysis

Cyclic diguanosine monophosphate represses bacterial flagella synthesis by interacting with the Walker A motif of the enhancer-binding protein FleQ

The N‐terminal FleQ domain of the Vibrio cholerae flagellar master regulator FlrA plays pivotal structural roles in stabilizing its active state

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