A Mutational Study of Cnu Reveals Attractive Forces between Cnu and H-NS

Yun, Sang Hoon; Ji, Sang Chun; Jeon, Heung Jin; Wang, Xun; Lee, Younghoon; Choi, Byong‐Seok; Lim, Heon M.

doi:10.1007/s10059-012-0006-5

Cited by 4 publications

(4 citation statements)

References 29 publications

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“…The initial purpose of these experiments was to understand the mechanism of interaction between the Cnu and H-NS proteins by isolating Cnu variants unable to interact with H-NS [22] . The selection criteria for the Cnu variants were based on our previous in vivo results, and were performed at 37°C.…”

Section: Resultsmentioning

confidence: 99%

The CnuK9E H-NS Complex Antagonizes DNA Binding of DicA and Leads to Temperature-Dependent Filamentous Growth in E. coli

Yun

Jeon

et al. 2012

PLoS ONE

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Cnu (an OriC-binding nucleoid protein) associates with H-NS. A variant of Cnu was identified as a key factor for filamentous growth of a wild-type Escherichia coli strain at 37°C. This variant (CnuK9E) bears a substitution of a lysine to glutamic acid, causing a charge reversal in the first helix. The temperature-dependent filamentous growth of E. coli bearing CnuK9E could be reversed by either lowering the temperature to 25°C or lowering the CnuK9E concentration in the cell. Gene expression analysis suggested that downregulation of dicA by CnuK9E causes a burst of dicB transcription, which, in turn, elicits filamentous growth. In vivo assays indicated that DicA transcriptionally activates its own gene, by binding to its operator in a temperature-dependent manner. The antagonizing effect of CnuK9E with H-NS on DNA-binding activity of DicA was stronger at 37°C, presumably due to the lower operator binding of DicA at 37°C. These data suggest that the temperature-dependent negative effect of CnuK9E on DicA binding plays a major role in filamentous growth. The C-terminus of DicA shows significant amino acid sequence similarity to the DNA-binding domains of RovA and SlyA, regulators of pathogenic genes in Yersinia and Salmonella, respectively, which also show better DNA-binding activity at 25°C.

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Section: Resultsmentioning

confidence: 99%

The CnuK9E H-NS Complex Antagonizes DNA Binding of DicA and Leads to Temperature-Dependent Filamentous Growth in E. coli

Yun

Jeon

et al. 2012

PLoS ONE

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“… 45 ). YdgT can interact with H-NS and StpA ( 18 , 97 ), but may have effects similar to or different from Hha ( 39 , 63 ). Finally, our results provide more evidence that Hha enhances bridging of H-NS filaments ( 17 , 39 ) and possibly induces compaction ( 62 ); however, it remains unclear how Hha might drive H-NS to favor a multi-bridged conformation or how H-NS modulator proteins could reorganize H-NS filaments.…”

Section: Discussionmentioning

confidence: 99%

StpA and Hha stimulate pausing by RNA polymerase by promoting DNA–DNA bridging of H-NS filaments

Boudreau

Hron

Qin

et al. 2018

Nucleic Acids Research

106

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In enterobacteria, AT-rich horizontally acquired genes, including virulence genes, are silenced through the actions of at least three nucleoid-associated proteins (NAPs): H-NS, StpA and Hha. These proteins form gene-silencing nucleoprotein filaments through direct DNA binding by H-NS and StpA homodimers or heterodimers. Both linear and bridged filaments, in which NAPs bind one or two DNA segments, respectively, have been observed. Hha can interact with H-NS or StpA filaments, but itself lacks a DNA-binding domain. Filaments composed of H-NS alone can inhibit transcription initiation and, in the bridged conformation, slow elongating RNA polymerase (RNAP) by promoting backtracking at pause sites. How the other NAPs modulate these effects of H-NS is unknown, despite evidence that they help regulate subsets of silenced genes in vivo (e.g. in pathogenicity islands). Here we report that Hha and StpA greatly enhance H-NS-stimulated pausing by RNAP at 20°C. StpA:H-NS or StpA-only filaments also stimulate pausing at 37°C, a temperature at which Hha:H-NS or H-NS-only filaments have much less effect. In addition, we report that both Hha and StpA greatly stimulate DNA–DNA bridging by H-NS filaments. Together, these observations indicate that Hha and StpA can affect H-NS-mediated gene regulation by stimulating bridging of H-NS/DNA filaments.

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“…Regarding additional oriBPs in E. coli , the CspD protein reportedly inhibits both the initiation and elongation of chromosomal replication in vitro (Yamanaka et al, 2001 ). Finally, additional proteins capable of specifically binding oriC have been identified and described (e.g., Rob, H-NS, and DpiA), but their specific roles and contributions to the replication initiation process are not yet known (Skarstad et al, 1993 ; Martin et al, 1999 ; Miller et al, 2003 ; Kim et al, 2005 ; Yun et al, 2012a , b ).…”

Section: Oric Activity Is Regulated By Specific Origin-bindimentioning

confidence: 99%

oriC-encoded instructions for the initiation of bacterial chromosome replication

et al. 2015

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Replication of the bacterial chromosome initiates at a single origin of replication that is called oriC. This occurs via the concerted action of numerous proteins, including DnaA, which acts as an initiator. The origin sequences vary across species, but all bacterial oriCs contain the information necessary to guide assembly of the DnaA protein complex at oriC, triggering the unwinding of DNA and the beginning of replication. The requisite information is encoded in the unique arrangement of specific sequences called DnaA boxes, which form a framework for DnaA binding and assembly. Other crucial sequences of bacterial origin include DNA unwinding element (DUE, which designates the site at which oriC melts under the influence of DnaA) and binding sites for additional proteins that positively or negatively regulate the initiation process. In this review, we summarize our current knowledge and understanding of the information encoded in bacterial origins of chromosomal replication, particularly in the context of replication initiation and its regulation. We show that oriC encoded instructions allow not only for initiation but also for precise regulation of replication initiation and coordination of chromosomal replication with the cell cycle (also in response to environmental signals). We focus on Escherichia coli, and then expand our discussion to include several other microorganisms in which additional regulatory proteins have been recently shown to be involved in coordinating replication initiation to other cellular processes (e.g., Bacillus, Caulobacter, Helicobacter, Mycobacterium, and Streptomyces). We discuss diversity of bacterial oriC regions with the main focus on roles of individual DNA recognition sequences at oriC in binding the initiator and regulatory proteins as well as the overall impact of these proteins on the formation of initiation complex.

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A Mutational Study of Cnu Reveals Attractive Forces between Cnu and H-NS

Cited by 4 publications

References 29 publications

The CnuK9E H-NS Complex Antagonizes DNA Binding of DicA and Leads to Temperature-Dependent Filamentous Growth in E. coli

The CnuK9E H-NS Complex Antagonizes DNA Binding of DicA and Leads to Temperature-Dependent Filamentous Growth in E. coli

StpA and Hha stimulate pausing by RNA polymerase by promoting DNA–DNA bridging of H-NS filaments

oriC-encoded instructions for the initiation of bacterial chromosome replication

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