Regulation of the
 yjjQ
 -
 bglJ
 Operon, Encoding LuxR-Type Transcription Factors, and the Divergent
 yjjP
 Gene by H-NS and LeuO

Stratmann, Thomas; Madhusudan, Srinivasan; Schnetz, Karin

doi:10.1128/jb.01447-07

Cited by 48 publications

(77 citation statements)

References 59 publications

(92 reference statements)

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“…Further, the RcsA protein is a substrate of the ATP-dependent Lon protease, which adds a further level of control on RcsA (14). The bglJ gene is the second gene of the H-NS repressed yjjQ-bglJ operon that can be activated by the pleiotropic transcription regulator LeuO (54). However, the leuO gene is also repressed by H-NS at standard laboratory growth conditions.…”

Section: Discussionmentioning

confidence: 99%

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Interaction of the RcsB Response Regulator with Auxiliary Transcription Regulators in Escherichia coli

Pannen

Fabisch

Gausling

et al. 2016

Journal of Biological Chemistry

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The Rcs phosphorelay is a two-component signal transduction system that is induced by cell envelope stress. RcsB, the response regulator of this signaling system, is a pleiotropic transcription regulator, which is involved in the control of various stress responses, cell division, motility, and biofilm formation. RcsB regulates transcription either as a homodimer or together with auxiliary regulators, such as RcsA, BglJ, and GadE in Escherichia coli. In this study, we show that RcsB in addition forms heterodimers with MatA (also known as EcpR) and with DctR. Our data suggest that the MatA-dependent transcription regulation is mediated by the MatA-RcsB heterodimer and is independent of RcsB phosphorylation. Furthermore, we analyzed the relevance of amino acid residues of the active quintet of conserved residues, and of surface-exposed residues for activity of RcsB. The data suggest that the activity of the phosphorylation-dependent dimers, such as RcsA-RcsB and RcsB-RcsB, is affected by mutation of residues in the vicinity of the phosphorylation site, suggesting that a phosphorylation-induced structural change modulates their activity. In contrast, the phosphorylation-independent heterodimers BglJ-RcsB and MatA-RcsB are affected by only very few mutations. Heterodimerization of RcsB with various auxiliary regulators and their differential dependence on phosphorylation add an additional level of control to the Rcs system that is operating at the output level.

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Section: Discussionmentioning

confidence: 99%

“…One of the main elements in this control is the availability of the interaction partners. Expression of all of the corresponding genes is repressed by the nucleoid-associated and global repressor protein H-NS (22,47,54,55) (Fig. 7).…”

Section: Discussionmentioning

confidence: 99%

Interaction of the RcsB Response Regulator with Auxiliary Transcription Regulators in Escherichia coli

Pannen

Fabisch

Gausling

et al. 2016

Journal of Biological Chemistry

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“…This effect would be overcome by V. cholerae regulatory proteins that, under appropriate environmental conditions, could act as antirepressors to alleviate the effects of H-NS on tcp and ctx expression. Indeed, several bacterial regulatory proteins are known to alleviate H-NS repression by displacing H-NS from the DNA (8,38,61,63). At the tcpA promoter we have previously reported that both ToxT and IHF act as antirepressors of H-NS (60).…”

Section: Discussionmentioning

confidence: 99%

H-NS Binding and Repression of the ctx Promoter in Vibrio cholerae

et al. 2011

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Expression of the ctx and tcp genes, which encode cholera toxin and the toxin coregulated pilus, the Vibrio cholerae O1 virulence determinants having the largest contribution to cholera disease, is repressed by the nucleoid-associated protein H-NS and activated by the AraC-like transcriptional regulator ToxT. To elucidate the molecular mechanism by which H-NS controls transcription of the ctxAB operon, H-NS repression and binding were characterized by using a promoter truncation series, gel mobility shift assays, and DNase I footprinting. Promoter regions found to be important for H-NS repression correlated with in vitro binding. Four main H-NS binding regions are present at ctx. One region overlaps the high-affinity ToxT binding site and extends upstream, another overlaps the ToxT low-affinity binding site around the ؊35 element, and the remaining two are located adjacent to one another downstream of the transcriptional start site. Competition for binding to the overlapping H-NS/ToxT binding sites was observed in gel mobility shift assays, where ToxT was found to displace H-NS from the ctx promoter region. In addition, regulatory differences between the ctx and tcpA promoters were examined. H-NS was found to have a higher relative binding affinity for the ctx promoter than for the tcpA promoter in vitro. In contrast to ToxT-dependent activation of the tcpA promoter, ToxT activation of ctx did not require the C-terminal domain of the ␣-subunit of RNA polymerase. These findings demonstrate that transcriptional regulation of ctx and tcpA by H-NS and ToxT is mechanistically distinct, and this may lead to important differences in the expression of these coregulated genes.Vibrio cholerae is the etiological agent of the human diarrheal disease cholera. Two virulence factors that are produced by V. cholerae and are essential for disease are toxin-coregulated pilus (TCP) (62) and cholera toxin (CT) (28). TCP is a type IV pilus that is assembled by polymerization of the pilin subunit, TcpA, and forms long filaments that laterally associate into bundles. Expression of TCP in vitro results in autoagglutination of the bacterium, and TCP-mediated bacterium-bacterium interactions in vivo facilitate microcolony formation on the intestinal epithelium. Pilus biogenesis requires at least 9 other proteins in addition to TcpA, which are encoded in an operon located on the Vibrio pathogenicity island (VPI). The pilus biogenesis apparatus plays a second role in colonization by secreting the cotranscribed, soluble colonization factor TcpF, which is also essential for colonization but for which a mechanism remains unknown (29, 30). The second main virulence factor, CT, is a potent A 1 B 5 subunit, ADP-ribosylating toxin that is responsible for the severe watery diarrhea that is associated with cholera. CT is encoded by the ctxAB operon, which is located on the lysogenic bacteriophage CTX. The VPI and CTX were both acquired by horizontal gene transfer. TCP serves as the high-affinity receptor for CTX that links TCP production to ctx acq...

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“…Thus, a single protein may counter silencing by more than one mechanism. The LysR family regulator LeuO counters H-NS silencing of the putative virulence gene yjjQ in avian pathogenic E. coli [52] and H-NS/StpA silencing of the ompS1 porin gene in Salmonella [53]. The importance of H-NS in regulating horizontal gene transfer is not limited to pathogenesis.…”

Section: Counter-silencing Of H-ns and Its Functional Consequencesmentioning

confidence: 99%

New insights into transcriptional regulation by H-NS

Fang

Rimsky

2008

Current Opinion in Microbiology

186

173

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H-NS, a nucleoid-associated DNA-binding protein of enteric bacteria, was discovered thirty-five years ago and subsequently found to exert widespread and highly pleiotropic effects on gene regulation. H-NS binds to high-affinity sites and spreads along adjacent AT-rich DNA to silence transcription. Preferential binding to sequences with higher AT-content than the resident genome allows H-NS to repress the expression of foreign DNA in a process known as "xenogeneic silencing." Counter-silencing by a variety of mechanisms facilitates the evolutionary acquisition of horizontally transferred genes and their integration into pre-existing regulatory networks. This review will highlight recent insights into the mechanism and biological importance of H-NS-DNA interactions. H-NS--A Nucleoid ProteinH-NS is an abundant DNA-binding protein implicated in the organization of the bacterial chromosome [1]. H-NS and other nucleoid-associated proteins can affect DNA topology at specific loci, thereby modulating gene transcription. Binding by these proteins is proposed to selectively direct supercoiling effects to promoters [2•]. Mutation of hns alters the responsiveness of transcription to changes in DNA superhelicity. Regulatory effects of supercoiling are linked to metabolic and environmental conditions. Thus, H-NS has been viewed as a nucleoid structuring protein with global effects on gene expression [3].H-NS exists primarily as a dimer at low concentrations but can multimerize into higher order complexes [4,5] that form bridges between adjacent DNA helices [6]. Optical tweezers have been used to demonstrate that H-NS dimers or multimers can simultaneously interact with separate DNA binding sites [7••]. H-NS-coated DNA is not self-interactive, suggesting that dimerization or oligomerization must precede DNA binding for bridging to occur. Force measurements suggest that transcription barriers created by H-NS binding are weak (∼7 pN) and readily overcome, so that H-NS oligomers pose only a relative barrier to translocating RNA polymerase. DNA bridging is a conserved feature of H-NS homologs found in most gram-negative bacteria [8] that appears to constrain large DNA loops [9••] and helps to account for the effects of H-NS on transcription. However, it must be noted that the relationship between bridging as a general effect and the silencing of specific promoters is not yet clear.H-NS is more appropriately viewed as a determinant of chromosomal architecture rather than as a general structural component. The analysis of nucleoids treated with urea suggests that *Corresponding Author : Tel 206-275-0966, Fax 206-616-1575, e-mail : fcfang@u.washington.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production proce...

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Regulation of the yjjQ - bglJ Operon, Encoding LuxR-Type Transcription Factors, and the Divergent yjjP Gene by H-NS and LeuO

Cited by 48 publications

References 59 publications

Interaction of the RcsB Response Regulator with Auxiliary Transcription Regulators in Escherichia coli

Interaction of the RcsB Response Regulator with Auxiliary Transcription Regulators in Escherichia coli

H-NS Binding and Repression of the ctx Promoter in Vibrio cholerae

New insights into transcriptional regulation by H-NS

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