5DMB image
Entry Detail
PDB ID:
5DMB
Keywords:
Title:
Crystal structure of a translational regulator bound to a flagellar assembly factor
Biological Source:
PDB Version:
Deposition Date:
2015-09-08
Release Date:
2016-08-24
Method Details:
Experimental Method:
Resolution:
2.30 Å
R-Value Free:
0.28
R-Value Work:
0.22
R-Value Observed:
0.22
Space Group:
C 1 2 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Flagellar assembly factor FliW
Chain IDs:A
Chain Length:151
Number of Molecules:1
Biological Source:Geobacillus thermodenitrificans
Polymer Type:polypeptide(L)
Description:Carbon storage regulator homolog
Chain IDs:B (auth: D)
Chain Length:83
Number of Molecules:1
Biological Source:Geobacillus thermodenitrificans
Primary Citation
Structural basis for the CsrA-dependent modulation of translation initiation by an ancient regulatory protein.
Proc.Natl.Acad.Sci.USA 113 10168 10173 (2016)
PMID: 27551070 DOI: 10.1073/pnas.1602425113

Abstact

Regulation of translation is critical for maintaining cellular protein levels, and thus protein homeostasis. The conserved RNA-binding protein CsrA (also called RsmA; for carbon storage regulator and regulator of secondary metabolism, respectively; hereafter called CsrA) represents a well-characterized example of regulation at the level of translation initiation in bacteria. Binding of a CsrA homodimer to the 5'UTR of an mRNA occludes the Shine-Dalgarno sequence, blocking ribosome access for translation. Small noncoding RNAs (sRNAs) can competitively antagonize CsrA activity by a well-understood mechanism. However, the regulation of CsrA by the protein FliW is just emerging. FliW antagonizes the CsrA-dependent repression of translation of the flagellar filament protein, flagellin. Crystal structures of the FliW monomer reveal a novel, minimal β-barrel-like fold. Structural analysis of the CsrA/FliW heterotetramer shows that FliW interacts with a C-terminal extension of CsrA. In contrast to the competitive regulation of CsrA by sRNAs, FliW allosterically antagonizes CsrA in a noncompetitive manner by excluding the 5'UTR from the CsrA-RNA binding site. Our phylogenetic analysis shows that the FliW-mediated regulation of CsrA regulation is the ancestral state in flagellated bacteria. We thus demonstrate fundamental mechanistic differences in the regulation of CsrA by sRNA in comparison with an ancient regulatory protein.

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