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Mechanisms for Hfq-Independent Activation of rpoS by DsrA, a Small RNA, in Escherichia coli
Ist Teil von
Molecules and Cells, 2019, 42(5), , pp.426-439
Ort / Verlag
United States: Korean Society for Molecular and Cellular Biology
Erscheinungsjahr
2019
Link zum Volltext
Quelle
SpringerLink
Beschreibungen/Notizen
Many small RNAs (sRNAs) regulate gene expression by base pairing to their target messenger RNAs (mRNAs) with the help of Hfq in
. The sRNA DsrA activates translation of the
mRNA in an Hfq-dependent manner, but this activation ability was found to partially bypass Hfq when DsrA is overproduced. The precise mechanism by which DsrA bypasses Hfq is unknown. In this study, we constructed strains lacking all three
-activating sRNAs (i.e., ArcZ, DsrA, and RprA) in
and
backgrounds, and then artificially regulated the cellular DsrA concentration in these strains by controlling its ectopic expression. We then examined how the expression level of
was altered by a change in the concentration of DsrA. We found that the translation and stability of the
mRNA are both enhanced by physiological concentrations of DsrA regardless of Hfq, but that depletion of Hfq causes a rapid degradation of DsrA and thereby decreases
mRNA stability. These results suggest that the observed Hfq dependency of DsrA-mediated
activation mainly results from the destabilization of DsrA in the absence of Hfq, and that DsrA itself contributes to the translational activation and stability of the
mRNA in an Hfq-independent manner.