| Structural highlights
Function
[HFQ_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 PubMed
In Escherichia coli the RNA chaperone Hfq is involved in riboregulation by assisting base-pairing between small regulatory RNAs (sRNAs) and mRNA targets. Several structural and biochemical studies revealed RNA binding sites on either surface of the donut shaped Hfq-hexamer. Whereas sRNAs are believed to contact preferentially the YKH motifs present on the proximal site, poly(A)(15) and ADP were shown to bind to tripartite binding motifs (ARE) circularly positioned on the distal site. Hfq has been reported to bind and to hydrolyze ATP. Here, we present the crystal structure of a C-terminally truncated variant of E. coli Hfq (Hfq(65)) in complex with ATP, showing that it binds to the distal R-sites. In addition, we revisited the reported ATPase activity of full length Hfq purified to homogeneity. At variance with previous reports, no ATPase activity was observed for Hfq. In addition, FRET assays neither indicated an impact of ATP on annealing of two model oligoribonucleotides nor did the presence of ATP induce strand displacement. Moreover, ATP did not lead to destabilization of binary and ternary Hfq-RNA complexes, unless a vast stoichiometric excess of ATP was used. Taken together, these studies strongly suggest that ATP is dispensable for and does not interfere with Hfq-mediated RNA transactions.
Structural and biochemical studies on ATP binding and hydrolysis by the Escherichia coli RNA chaperone Hfq.,Hammerle H, Beich-Frandsen M, Vecerek B, Rajkowitsch L, Carugo O, Djinovic-Carugo K, Blasi U PLoS One. 2012;7(11):e50892. doi: 10.1371/journal.pone.0050892. Epub 2012 Nov 30. PMID:23226421[11]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Carmichael GG, Weber K, Niveleau A, Wahba AJ. The host factor required for RNA phage Qbeta RNA replication in vitro. Intracellular location, quantitation, and purification by polyadenylate-cellulose chromatography. J Biol Chem. 1975 May 25;250(10):3607-612. PMID:805130
- ↑ Hajnsdorf E, Regnier P. Host factor Hfq of Escherichia coli stimulates elongation of poly(A) tails by poly(A) polymerase I. Proc Natl Acad Sci U S A. 2000 Feb 15;97(4):1501-5. PMID:10677490 doi:10.1073/pnas.040549897
- ↑ Sledjeski DD, Whitman C, Zhang A. Hfq is necessary for regulation by the untranslated RNA DsrA. J Bacteriol. 2001 Mar;183(6):1997-2005. PMID:11222598 doi:10.1128/JB.183.6.1997-2005.2001
- ↑ Guisbert E, Rhodius VA, Ahuja N, Witkin E, Gross CA. Hfq modulates the sigmaE-mediated envelope stress response and the sigma32-mediated cytoplasmic stress response in Escherichia coli. J Bacteriol. 2007 Mar;189(5):1963-73. Epub 2006 Dec 8. PMID:17158661 doi:10.1128/JB.01243-06
- ↑ Kim Y, Wood TK. Toxins Hha and CspD and small RNA regulator Hfq are involved in persister cell formation through MqsR in Escherichia coli. Biochem Biophys Res Commun. 2010 Jan 1;391(1):209-13. doi:, 10.1016/j.bbrc.2009.11.033. Epub 2009 Nov 10. PMID:19909729 doi:10.1016/j.bbrc.2009.11.033
- ↑ Carmichael GG, Weber K, Niveleau A, Wahba AJ. The host factor required for RNA phage Qbeta RNA replication in vitro. Intracellular location, quantitation, and purification by polyadenylate-cellulose chromatography. J Biol Chem. 1975 May 25;250(10):3607-612. PMID:805130
- ↑ Hajnsdorf E, Regnier P. Host factor Hfq of Escherichia coli stimulates elongation of poly(A) tails by poly(A) polymerase I. Proc Natl Acad Sci U S A. 2000 Feb 15;97(4):1501-5. PMID:10677490 doi:10.1073/pnas.040549897
- ↑ Sledjeski DD, Whitman C, Zhang A. Hfq is necessary for regulation by the untranslated RNA DsrA. J Bacteriol. 2001 Mar;183(6):1997-2005. PMID:11222598 doi:10.1128/JB.183.6.1997-2005.2001
- ↑ Guisbert E, Rhodius VA, Ahuja N, Witkin E, Gross CA. Hfq modulates the sigmaE-mediated envelope stress response and the sigma32-mediated cytoplasmic stress response in Escherichia coli. J Bacteriol. 2007 Mar;189(5):1963-73. Epub 2006 Dec 8. PMID:17158661 doi:10.1128/JB.01243-06
- ↑ Kim Y, Wood TK. Toxins Hha and CspD and small RNA regulator Hfq are involved in persister cell formation through MqsR in Escherichia coli. Biochem Biophys Res Commun. 2010 Jan 1;391(1):209-13. doi:, 10.1016/j.bbrc.2009.11.033. Epub 2009 Nov 10. PMID:19909729 doi:10.1016/j.bbrc.2009.11.033
- ↑ Hammerle H, Beich-Frandsen M, Vecerek B, Rajkowitsch L, Carugo O, Djinovic-Carugo K, Blasi U. Structural and biochemical studies on ATP binding and hydrolysis by the Escherichia coli RNA chaperone Hfq. PLoS One. 2012;7(11):e50892. doi: 10.1371/journal.pone.0050892. Epub 2012 Nov 30. PMID:23226421 doi:http://dx.doi.org/10.1371/journal.pone.0050892
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