H-NS Represses<i>inv</i>Transcription in<i>Yersinia enterocolitica</i>through Competition with RovA and Interaction with YmoA

Ellison, Damon W.; Miller, Virginia L.

doi:10.1128/jb.00862-05

Cited by 91 publications

(163 citation statements)

References 62 publications

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“…are repressed by H-NS, and most RovA-bound promoters are also bound by H-NS [61]. The Y. enterocolitica inv gene encoding invasin is repressed by H-NS in conjunction with Hha (called YmoA in Y. enterocolitica) [62] and derepressed by RovA. Interestingly, removal of the last four amino acid residues of RovA abolishes its ability to displace H-NS even though dimerization and DNA-binding in vitro are retained, leading to the suggestion that the C-terminus of RovA might interact with H-NS directly (or stabilize interactions with RNAP or other RovA dimers) [63].…”

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

188

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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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

188

173

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“…It has also been pointed out that the insertion of YmoA or Hha dimers into H-NS-DNA complexes may alter the supra-structuring of the nucleoprotein complexes in ways that alter biological function (McFeeters et al, 2007). In cases where the contribution of these proteins has been examined, such as inv gene repression in Y. enterocolitica, the effect of YmoA has been to enhance the repressive effect of H-NS (Ellison & Miller, 2006b) (Fig. 1i).…”

Section: Full-length Truncated and Partial Paralogues And Orthologuementioning

confidence: 99%

“…(Nasser & Reverchon, 2002), Proteus mirabilis (Coker et al, 2000), Shigella flexneri Prosseda et al, 2004), Vibrio cholerae (Ghosh et al, 2006;Nye et al, 2000) and Yersinia spp. (Cathelyn et al, 2007;Ellison & Miller, 2006b;Heroven et al, 2007).…”

Section: H-ns and Transcription Repressionmentioning

confidence: 99%

Anti-silencing: overcoming H-NS-mediated repression of transcription in Gram-negative enteric bacteria

2008

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“…Negative modulation of hilA is also accomplished by global modulators such as Hha (Fahlen et al, 2001) and H-NS (Olekhnovich & Kadner, 2006;Schechter et al, 2003). Both belong to the superfamily of the nucleoid-associated proteins (Dorman, 2004;Madrid et al, 2007) and have been shown to interact to modulate gene expression (Ellison & Miller, 2006;Madrid et al, 2002;Nieto et al, 1991Nieto et al, , 2002. The nucleoid-associated protein H-NS is a well-characterized example of a modulator that influences gene expression in response to environmental stimuli such as osmolarity, pH and temperature (Hulton et al, 1990;Hommais et al, 2001;Ono et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Integration host factor alleviates H-NS silencing of the Salmonella enterica serovar Typhimurium master regulator of SPI1, hilA

et al. 2011

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Coordination of the expression of Salmonella enterica invasion genes on Salmonella pathogenicity island 1 (SPI1) depends on a complex circuit involving several regulators that converge on expression of the hilA gene, which encodes a transcriptional activator (HilA) that modulates expression of the SPI1 virulence genes. Two of the global regulators that influence hilA expression are the nucleoid-associated proteins Hha and H-NS. They interact and form a complex that modulates gene expression. A chromosomal transcriptional fusion was constructed to assess the effects of these modulators on hilA transcription under several environmental conditions as well as at different stages of growth. The results obtained showed that these proteins play a role in silencing hilA expression at both low temperature and low osmolarity, irrespective of the growth phase. H-NS accounts for the main repressor activity. At high temperature and osmolarity, H-NS-mediated silencing completely ceases when cells enter the stationary phase, and hilA expression is induced. Mutants lacking IHF did not induce hilA in cells entering the stationary phase, and this lack of induction was dependent on the presence of H-NS. Band-shift assays and in vitro transcription data showed that for hilA induction under certain growth conditions, IHF is required to alleviate H-NS-mediated silencing.

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H-NS RepressesinvTranscription inYersinia enterocoliticathrough Competition with RovA and Interaction with YmoA

Cited by 91 publications

References 62 publications

New insights into transcriptional regulation by H-NS

New insights into transcriptional regulation by H-NS

Anti-silencing: overcoming H-NS-mediated repression of transcription in Gram-negative enteric bacteria

Integration host factor alleviates H-NS silencing of the Salmonella enterica serovar Typhimurium master regulator of SPI1, hilA

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