Posttranscriptional regulation of cspE in Escherichia coli: involvement of the short 5'-untranslated region.
Escherichia coli K-12 contains nine paralogs of CspA, namely CspA-CspI. In spite of considerable sequence similarity among these genes, the individual members of this family show significant differences in their expression regulation. Among these nine members, cspA, B, G and I have been reported to be cold-induced. The unusually long 5'-untranslated region (5'-UTR) of these four and other cold-induced genes has often been associated with their inducibility. Sequence analysis of the cspE upstream region revealed two promoter-like motifs having high scores. We identified the promoter site and established that cspE has a much shorter 5'-UTR compared to other cold-induced genes. Our results showed that cspE is induced to about threefold at both the transcript and the protein level in response to cold-shock. Its transcript half-life increases significantly upon cold-shock. Furthermore, we demonstrated that RNase E, a key endonuclease responsible for mRNA degradation in E. coli, regulates cspE transcript stability, possibly through the assembly of a degradosome. In silico analysis of the cspE 5'-UTR revealed alternative secondary structures at 37 and 15 degrees C. A point mutation that was predicted to relax the secondary structure of the 5'-UTR at 15 degrees C showed considerable reduction in transcript stability, indicating that alternative transcript secondary structures might be the cause of the differential stability.
Uppal
Sheetal
S
Bhabha Atomic Research Centre, Molecular Biology Division, Trombay, Mumbai, India.
Akkipeddi
Venkata S N Rao
VS
Jawali
Narendra
N
D020121:5' Untranslated Regions / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D003080:Cold Temperature; D004722:Endoribonucleases / Q000378:metabolism; D048168:Escherichia coli K12 / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D020871:RNA Stability; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics
D020121:5' Untranslated Regions; C088097:CspE protein, E coli; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D012329:RNA, Bacterial; D004722:Endoribonucleases; C022537:ribonuclease E