PNPase is a key player in the regulation of small RNAs that control the expression of outer membrane proteins.
In this report, we demonstrate that exonucleolytic turnover is much more important in the regulation of sRNA levels than was previously recognized. For the first time, PNPase is introduced as a major regulatory feature controlling the levels of the small noncoding RNAs MicA and RybB, which are required for the accurate expression of outer membrane proteins (OMPs). In the absence of PNPase, the pattern of OMPs is changed. In stationary phase, MicA RNA levels are increased in the PNPase mutant, leading to a decrease in the levels of its target ompA mRNA and the respective protein. This growth phase regulation represents a novel pathway of control. We have evaluated other ribonucleases in the control of MicA RNA, and we showed that degradation by PNPase surpasses the effect of endonucleolytic cleavages by RNase E. RybB was also destabilized by PNPase. This work highlights a new role for PNPase in the degradation of small noncoding RNAs and opens the way to evaluate striking similarities between bacteria and eukaryotes.
Andrade
José M
JM
Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2781-901 Oeiras, Portugal.
Arraiano
Cecília M
CM
D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D045647:DNA Glycosylases / Q000235:genetics / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008954:Models, Biological; D009154:Mutation; D011117:Polyribonucleotide Nucleotidyltransferase / Q000235:genetics* / Q000378:metabolism*; D020871:RNA Stability; D016372:RNA, Antisense / Q000235:genetics / Q000378:metabolism; D012329:RNA, Bacterial / Q000235:genetics* / Q000378:metabolism*; D022661:RNA, Untranslated / Q000235:genetics / Q000378:metabolism
D001425:Bacterial Outer Membrane Proteins; D017931:DNA Primers; D029968:Escherichia coli Proteins; D016372:RNA, Antisense; D012329:RNA, Bacterial; D022661:RNA, Untranslated; C078167:OMPA outer membrane proteins; D011117:Polyribonucleotide Nucleotidyltransferase; D045647:DNA Glycosylases; C061738:mutY adenine glycosylase