%0 Journal Article
%T Hfq affects mRNA levels independently of degradation
%A Jacques Le Derout
%A Irina V Boni
%A Philippe R¨¦gnier
%A Eliane Hajnsdorf
%J BMC Molecular Biology
%D 2010
%I BioMed Central
%R 10.1186/1471-2199-11-17
%X The role of Hfq in the maturation and degradation of the rpsO mRNA of E. coli was investigated in vivo. The data revealed a decrease in rpsO mRNA abundance concomitant to an increase in its stability when Hfq is absent. This indicates that the change in mRNA levels in hfq mutants does not result from its modification of RNA stability. Moreover, a series of independent experiments have revealed that the decrease in mRNA level is not a consequence of a reduction of translation efficiency and that Hfq is not directly implicated in translational control of rpsO expression. Reduced steady-state mRNA levels in the absence of Hfq were also shown for rpsT, rpsB and rpsB-tsf, but not for lpp, pnp or tRNA transcripts. The abundance of chimeric transcripts rpsO-lacZ and rpsB-lacZ, whose expression was driven by rpsO and rpsB promoters, respectively, was also lower in the hfq null-mutants, while the ¦Â-galactosidase yield remained about the same as in the parent wild-type strain.The data obtained suggest that alteration of rpsO, rpsT and rpsB-tsf transcript levels observed under conditions of Hfq deficiency is not caused by the post-transcriptional events, such as mRNA destabilization or changes in translation control, and may rather result from changes in transcriptional activity. So far, how Hfq affects transcription remains unclear. We propose that one of the likely mechanisms of Hfq-mediated modulation of transcription might operate early in the elongation step, when interaction of Hfq with a nascent transcript would help to overcome transcription pauses and to prevent preliminary transcript release.Hfq is an RNA binding protein initially identified as a host factor required for the replication of the phage Q¦Â RNA [1]. It was then demonstrated to belong to the Sm-like protein family involved in many RNA processing events in eukaryotes [2]. The Hfq-encoding gene is widely conserved in bacteria and found in many sequenced bacterial genomes [3]. Hfq is a highly abundant protein
%U http://www.biomedcentral.com/1471-2199/11/17