Structure and function of bacterial H-NS protein

The histone-like nucleoid structuring (H-NS) protein is a major component of the folded chromosome in Escherichia coli and related bacteria. Functions attributed to H-NS include management of genome evolution, DNA condensation, and transcription. The wide-ranging influence of H-NS is remarkable given the simplicity of the protein, a small peptide, possessing rudimentary determinants for self-association, hetero-oligomerisation and DNA binding. In this review, I will discuss our understanding of H-NS with a focus on these structural elements. In particular, I will consider how these interaction surfaces allow H-NS to exert its different effects.

Download Full-text

Deconstructing the structural conservation of distantly related bacterial nucleoid-associated proteins using functional chimeras

10.1101/804138 ◽

2019 ◽

Author(s):

Rogério F. Lourenço ◽

Saumya Saurabh ◽

Jonathan Herrmann ◽

Soichi Wakatsuki ◽

Lucy Shapiro

Keyword(s):

Dna Binding ◽

Caulobacter Crescentus ◽

Structural Elements ◽

Phylogenetic Groups ◽

Sequence Element ◽

Force Microscopy ◽

Associated Proteins ◽

Self Association ◽

And Function

ABSTRACTNucleoid-associated proteins (NAPs) are DNA-binding proteins critical for the organization and function of the bacterial chromosome. A subclass of NAPs, including Caulobacter crescentus GapR and Escherichia coli H-NS, preferentially bind AT-rich regions of the nucleoid, but phylogenetic groups that encode GapR rarely encode H-NS. Here, utilizing genetic, biochemical, and biophysical studies of GapR in light of a recent DNA-bound crystal structure of GapR (Guo et al, 2018), we show that although evolutionarily distant, GapR and H-NS possess two regions that are structurally and functionally conserved. These regions are involved in self-association and DNA-binding, even though the two proteins oligomerize and regulate transcription differently. Functional analysis of GapR and H-NS protein chimeras identified structural elements present in H-NS but absent in GapR that rationalize differences in transcriptional regulation. In addition, we identified a sequence element unique to GapR that enables assembly into its tetrameric state. Using fluid-atomic force microscopy, we showed that GapR is capable of bridging DNA molecules in vitro. Together, these results demonstrate that two distantly related NAPs utilize evolutionarily conserved structural elements to serve specialized cellular roles via distinct mechanisms.

Download Full-text

Micro-analysis of pure deoxyribonucleic acid-dependent ribonucleic acid polymerase from Escherichia coli. Action of heparin and rifampicin on structure and function

Biochemical Journal ◽

10.1042/bj1170623 ◽

1970 ◽

Vol 117 (3) ◽

pp. 623-631 ◽

Cited By ~ 35

Author(s):

Volker Neuhoff ◽

Wolf-Bernhard Schill ◽

Hans Sternbach

Keyword(s):

Escherichia Coli ◽

Rna Polymerase ◽

Rna Synthesis ◽

Deoxyribonucleic Acid ◽

Structure And Function ◽

Disc Electrophoresis ◽

Inhibitory Mechanism ◽

And Function ◽

Micro Analysis ◽

Template Complex

By using micro disc electrophoresis and micro-diffusion techniques, the interaction of pure DNA-dependent RNA polymerase (EC 2.7.7.6) from Escherichia coli with the template, the substrates and the inhibitors heparin and rifampicin was investigated. The following findings were obtained: (1) heparin converts the 24S and 18S particles of the polymerase into the 13S form; (2) heparin inhibits RNA synthesis by dissociating the enzyme–template complex; (3) rifampicin does not affect the attachment of heparin to the enzyme; (4) the substrates ATP and UTP are bound by enzyme loaded with rifampicin; (5) rifampicin is bound by an enzyme–template complex to the same extent as by an RNA-synthesizing enzyme–template complex. From this it is concluded that the mechanism of the inhibition of RNA synthesis by rifampicin is radically different from that by heparin. As a working hypothesis to explain the inhibitory mechanism of rifampicin, it is assumed that it becomes very firmly attached to a position close to the synthesizing site and only blocks this when no synthesis is in progress.

Download Full-text

Influence of High Pressure on the Dimerization of ToxR, a Protein Involved in Bacterial Signal Transduction

Applied and Environmental Microbiology ◽

10.1128/aem.02028-08 ◽

2008 ◽

Vol 74 (24) ◽

pp. 7821-7823 ◽

Cited By ~ 14

Author(s):

Kai Linke ◽

Nagarajan Periasamy ◽

Matthias Ehrmann ◽

Roland Winter ◽

Rudi F. Vogel

Keyword(s):

Escherichia Coli ◽

Signal Transduction ◽

High Pressure ◽

Structure And Function ◽

Transmembrane Segments ◽

Bacterial Signal Transduction ◽

Reporter Strains ◽

And Function ◽

First Time

ABSTRACT High hydrostatic pressure (HHP) is suggested to influence the structure and function of membranes and/or integrated proteins. We demonstrate for the first time HHP-induced dimer dissociation of membrane proteins in vivo with Vibrio cholerae ToxR variants in Escherichia coli reporter strains carrying ctx::lacZ fusions. Dimerization ceased at 20 to 50 MPa depending on the nature of the transmembrane segments rather than on changes in the ToxR lipid bilayer environment.

Download Full-text