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Báo cáo khoa học: Stimulation of poly(A) synthesis by Escherichia coli poly(A)polymerase I is correlated with Hfq binding to poly(A) tails

The bacterial Lsm protein, host factor I (Hfq), is an RNA chaperone involved in many types of RNA transactions such as replication and stabil-ity, control of small RNA activity and polyadenylation. In this latter case, Hfq stimulates poly(A) synthesis and binds poly(A) tails that it protects from exonucleolytic degradation. We show here, that there is a correlation between Hfq binding to the 3¢ end of an RNA molecule and its ability to stimulate RNA elongation catalyzed by poly(A)polymerase I. | iFEBS Journal Stimulation of poly A synthesis by Escherichia coli poly A polymerase I is correlated with Hfq binding to poly A tails Marc Folichon Frederic Allemand Philippe Regnier and Eliane Hajnsdorf UPR CNRS 9073 conventionnee avec l Universite Paris 7 - Denis Diderot Institut de Biologie Physico-Chimique Paris France Keywords E. coli Hfq protein poly A -polymerase I polynucleotide phosphorylase RNA-protein interaction Correspondence E. Hajnsdorf UPR CNRS 9073 conventionnee avec l Universite Paris 7 - Denis Diderot Institut de Biologie Physico-Chimique 13 rue Pierre et Marie Curie 75005 Paris France Fax 33 1 58 41 50 20 Tel 33 1 58 41 51 26 E-mail Eliane.Hajnsdorf@ibpc.fr Received 16 September 2004 revised 15 November 2004 accepted 16 November 2004 doi 10.1111 j.1742-4658.2004.04485.x The bacterial Lsm protein host factor I Hfq is an RNA chaperone involved in many types of RNA transactions such as replication and stability control of small RNA activity and polyadenylation. In this latter case Hfq stimulates poly A synthesis and binds poly A tails that it protects from exonucleolytic degradation. We show here that there is a correlation between Hfq binding to the 3 end of an RNA molecule and its ability to stimulate RNA elongation catalyzed by poly A polymerase I. In contrast formation of the Hfq-RNA complex inhibits elongation of the RNA by polynucleotide phosphorylase. We demonstrate also that Hfq binding is not affected by the phosphorylation status of the RNA molecule and occurs equally well at terminal or internal stretches of poly A . Host factor I Hfq is an abundant protein of Escherichia coli which was first identified as a host factor required for the replication of Qb bacteriophage 1 . It has then been established that disruption of the hfq gene causes pronounced pleiotropic phenotypes in uninfected E. coli 2 and that in other bacteria Hfq permits the adaptation to multiple environmental stresses 3 4 . There is now an accumulation of data that shows .