期刊
GENES & DEVELOPMENT
卷 25, 期 19, 页码 2106-2117出版社
COLD SPRING HARBOR LAB PRESS, PUBLICATIONS DEPT
DOI: 10.1101/gad.16746011
关键词
Hfq RNA complex; crystal structure; NMR; DsrA; rpoS; Hfq cooperation; ADP
资金
- National Basic Research Program of China (973 Program) [2011CB966302, 2011CB911104]
- Chinese National Natural Science Foundation [30830031]
- Chinese Academy of Sciences [2006AA02A315]
Hfq is a bacterial post-transcriptional regulator. It facilitates base-pairing between sRNA and target mRNA. Hfq mediates DsrA-dependent translational activation of rpoS mRNA at low temperatures. rpoS encodes the stationary-phase sigma factor sigma(S), which is the central regulator in general stress response. However, structural information on Hfq-DsrA interaction is not yet available. Although Hfq is reported to hydrolyze ATP, the ATP-binding site is still unknown. Here, we report a ternary crystal complex structure of Escherichia coli Hfq bound to a major Hfq recognition region on DsrA (AU(6)A) together with ADP, and a crystal complex structure of Hfq bound to ADP. AU(6)A binds to the proximal and distal sides of two Hfq hexamers. ADP binds to a purine-selective site on the distal side and contacts conserved arginine or glutamine residues on the proximal side of another hexamer. This binding mode is different from previously postulated. The cooperation of two different Hfq hexamers upon nucleic acid binding in solution is verified by fluorescence polarization and solution nuclear magnetic resonance (NMR) experiments using fragments of Hfq and DsrA. Fluorescence resonance energy transfer conducted with full-length Hfq and DsrA also supports cooperation of Hfq hexamers upon DsrA binding. The implications of Hfq hexamer cooperation have been discussed.
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