5JAK: Crystal Structure Of The Flagellar Assembly Factor Fliw

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 beta-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.
PDB ID: 5JAKDownload
MMDB ID: 142283
PDB Deposition Date: 2016/4/12
Updated in MMDB: 2016/09
Experimental Method:
x-ray diffraction
Resolution: 1.8  Å
Source Organism:
Similar Structures:
Biological Unit for 5JAK: monomeric; determined by software (PISA)
Molecular Components in 5JAK
Label Count Molecule
Protein (1 molecule)
Flagellar Assembly Factor Fliw
Molecule annotation
* Click molecule labels to explore molecular sequence information.

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