Multimeric Self-assembly Equilibria Involving the Histone-like Protein H-NS

Ceschini, Simona; Lupidi, Giulio; Coletta, Massimo; Pon, Cynthia L.; Fioretti, Evandro; Angeletti, Mauro

doi:10.1074/jbc.275.2.729

Cited by 61 publications

(63 citation statements)

References 27 publications

(25 reference statements)

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“…At the protein concentration used in these experiments, it is clearly established that the equilibrium concentration of wildtype H-NS monomer is extremely small (22,37). The 1.8 S component of H-NS in velocity experiments is thus at least a dimer.…”

Section: Oligomerization State Of the Various H-ns Proteins In Solutimentioning

confidence: 90%

“…The biphasic nature of the dependence of the rate constant for monomer disappearance when the total protein concentration is increased is fairly accounted for by the lower reactivity of the polymerization interface. Indeed, the increase in the corresponding rate constant occurs in a protein concentration range where the fraction of H-NS oligomers higher than the dimer becomes significant in solution (22,37).…”

Section: Discussionmentioning

confidence: 99%

“…The corresponding dissociation constants K 1 (ϳ10 Ϫ7 M) and K 2 (ϳ10 Ϫ5 M) are sensitive to ionic strength and to temperature (22). It is clear that a mechanistic model is needed to explain how the association interfaces involved in the oligomerization of H-NS in solution are rearranged during the formation of specific and nonspecific assemblies on a given DNA template.…”

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confidence: 99%

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The Degree of Oligomerization of the H-NS Nucleoid Structuring Protein Is Related to Specific Binding to DNA

Badaut

Williams

Arluison

et al. 2002

Journal of Biological Chemistry

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At several E. coli promoters, initiation of transcription is repressed by a tight nucleoprotein complex formed by the assembly of the H-NS protein. In order to characterize the relationship between the structure of H-NS oligomers in solution and on relevant DNA fragments, we have compared wild-type H-NS and several transdominant H-NS mutants using gel shift assays, DNase I footprinting, analytical ultracentrifugation, and reactivity toward a cross-linking reagent. In solution, oligomerization occurs through two protein interfaces, one necessary to construct a dimeric core (and involving residues 1-64) and the other required for subsequent assembly of these dimers. We show that, as well as region 64 -95, residues present in the NH 2 -terminal coiled coil domain also participate in this second interface. Our results support the view that the same interacting interfaces are also involved on the DNA. We propose that the dimeric core recognizes specific motifs, with the second interface being critical for their correct head to tail assembly. The COOH-terminal domain of the protein contains the DNA binding motif essential for the discrimination of this specific functional assembly over competitive nonspecific H-NS polymers.

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Section: Oligomerization State Of the Various H-ns Proteins In Solutimentioning

confidence: 90%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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The Degree of Oligomerization of the H-NS Nucleoid Structuring Protein Is Related to Specific Binding to DNA

Badaut

Williams

Arluison

et al. 2002

Journal of Biological Chemistry

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“…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••].…”

Section: H-ns--a Nucleoid Proteinmentioning

confidence: 99%

“…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••].…”

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confidence: 99%

New insights into transcriptional regulation by H-NS

Fang

Rimsky

2008

Current Opinion in Microbiology

183

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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MucR binds multiple target sites in the promoter of its own gene and is a heat‐stable protein: Is MucR a H‐NS‐like protein?

et al. 2018

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The protein MucR from Brucella spp. is involved in the expression regulation of genes necessary for host interaction and infection. MucR is a member of the Ros/MucR family, which comprises prokaryotic zinc‐finger proteins and includes Ros from Agrobacterium tumefaciens and the Ml proteins from Mesorhizobium loti. MucR from Brucella spp. can regulate the expression of virulence genes and repress its own gene expression. Despite the well‐known role played by MucR in the repression of its own gene, no target sequence has yet been identified in the mucR promoter gene. In this study, we provide the first evidence that MucR from Brucella abortus binds more than one target site in the promoter region of its own gene, suggesting a molecular mechanism by which this protein represses its own expression. Furthermore, a circular dichroism analysis reveals that MucR is a heat‐stable protein. Overall, the results of this study suggest that MucR might resemble a H‐NS protein.

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Multimeric Self-assembly Equilibria Involving the Histone-like Protein H-NS

Cited by 61 publications

References 27 publications

The Degree of Oligomerization of the H-NS Nucleoid Structuring Protein Is Related to Specific Binding to DNA

The Degree of Oligomerization of the H-NS Nucleoid Structuring Protein Is Related to Specific Binding to DNA

New insights into transcriptional regulation by H-NS

MucR binds multiple target sites in the promoter of its own gene and is a heat‐stable protein: Is MucR a H‐NS‐like protein?

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