Effects of Hfq and RNAse E on the steady-state levels of DsrA, RyhB, SsrS, and SsrA RNAs and on the half-life of RyhB. (A) Hfq affects the half-life of RyhB sRNA. Graphical representation of RyhB RNA decay in an hfq+ (•) and an hfq−strain (▴). The Northern-blot analysis was carried out as described in Materials and Methods using a labeled riboprobe comprising nucleotides 19–60 of RyhB RNA. (B) The steady-state levels of both DsrA and RyhB sRNA are increased in anrnets strain at the nonpermissive temperature. The full-length (F) and the truncated (T) forms of DsrA are indicated by arrows on the left. (C) Equal steady-state levels of SsrS RNA in the hfq− and rnets strains (lanes 2,4) when compared with the respective wild-type strains (lanes 1,3). (D) The steady-state levels of SsrA RNA in the hfq− strain and in the hfq+ strain are equivalent (lanes 1,2), whereas SsrA precursor RNA accumulates upon inactivation of RNase E (cf. lanes 3,4). (B,C,D, bottom) Detection of 5S rRNA (loading control). The Northern-blot analysis and detection of sRNAs in total RNA was performed as described in Materials and Methods.
