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From Proteopedia
RNA-RNA base stacking in the crystal structure of an Hfq6:RNA dimer
Structural highlights
FunctionHFQ_ECOLI RNA chaperone that binds small regulatory RNA (sRNAs) and mRNAs to facilitate mRNA translational regulation in response to envelope stress, environmental stress and changes in metabolite concentrations. Involved in the regulation of stress responses mediated by the sigma factors RpoS, sigma-E and sigma-32. Binds with high specificity to tRNAs. In vitro, stimulates synthesis of long tails by poly(A) polymerase I. Required for RNA phage Qbeta replication.[1] [2] [3] [4] [5] Seems to play a role in persister cell formation; upon overexpression decreases persister cell formation while deletion increases persister formation.[6] [7] [8] [9] [10] Publication Abstract from PubMedThe RNA-chaperone Hfq catalyses the annealing of bacterial small RNAs (sRNAs) with target mRNAs to regulate gene expression in response to environmental stimuli. Hfq acts on a diverse set of sRNA-mRNA pairs using a variety of different molecular mechanisms. Here, we present an unusual crystal structure showing two Hfq-RNA complexes interacting via their bound RNA molecules. The structure contains two Hfq6:A18 RNA assemblies positioned face-to-face, with the RNA molecules turned towards each other and connected via interdigitating base stacking interactions at the center. Biochemical data further confirm the observed interaction, and indicate that RNA-mediated contacts occur between Hfq-RNA complexes with various (ARN)X motif containing RNA sequences in vitro, including the stress response regulator OxyS and its target, fhlA. A systematic computational survey also shows that phylogenetically conserved (ARN)X motifs are present in a subset of sRNAs, some of which share similar modular architectures. We hypothesise that Hfq can co-opt RNA-RNA base stacking, an unanticipated structural trick, to promote the interaction of (ARN)X motif containing sRNAs with target mRNAs on a "speed-dating" fashion, thereby supporting their regulatory function. Intermolecular base stacking mediates RNA-RNA interaction in a crystal structure of the RNA chaperone Hfq.,Schulz EC, Seiler M, Zuliani C, Voigt F, Rybin V, Pogenberg V, Mucke N, Wilmanns M, Gibson TJ, Barabas O Sci Rep. 2017 Aug 29;7(1):9903. doi: 10.1038/s41598-017-10085-8. PMID:28852099[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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