Differential decay of a polycistronic Escherichia coli transcript is initiated by RNaseE-dependent endonucleolytic processing.
Differential expression of the genes expressing Pap pili in Escherichia coli was suggested to involve mRNAs with different stabilities. As the result of a post-transcriptional processing event, a papA gene-specific mRNA product (mRNA-A) accumulates in large excess relative to the primary mRNA-BA transcript. Our results show that the processed product, mRNA-A, is a translationally active molecule and that it is generated from the mRNA-BA precursor by an RNaseE-dependent mechanism. The processing did not occur under non-permissive conditions in an E. coli rne mutant strain with a temperature-sensitive RNaseE. The endonuclease RNaseE was previously described as being chiefly involved in the processing of the 9S precursor of 5S rRNA. A comparison of nucleotide sequences of mRNA-BA and three other RNAs processed by RNAseE revealed a conserved motif around the cleavage sites. Mutations abolishing the activity of either of two other endoribonucleases, RNaseIII and RNaseP, did not affect the pap mRNA processing event. However, a conditional mutation in the ams locus, causing altered stability of bulk mRNA in E. coli, led to reduced pap mRNA processing in a manner similar to the effect caused by RNaseE deficiency. Our findings are consistent with the idea that ams is related/allelic to rne. Absence of the processing event in the RNaseE mutant (rne-3071) strain led to a four-fold stabilization of the mRNA-BA primary transcript. We conclude that the RNaseE-dependent processing event is the rate-limiting step in the decay of the papB-coding part of the primary transcript and in the production of the stable mRNA-A product.(ABSTRACT TRUNCATED AT 250 WORDS)
Department of Microbiology, University of Umeå, Sweden.
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Nilsson
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Uhlin
D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis / Q000235:genetics*; D001483:Base Sequence; D004722:Endoribonucleases / Q000737:chemistry* / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D036781:Fimbriae Proteins; D015964:Gene Expression Regulation, Bacterial; D005796:Genes; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D012322:RNA Precursors / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional / Q000235:genetics*; D016337:RNA, Catalytic / Q000737:chemistry; D012333:RNA, Messenger / Q000096:biosynthesis*; D043244:Ribonuclease III; D043262:Ribonuclease P; D014158:Transcription, Genetic
D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; D012322:RNA Precursors; D016337:RNA, Catalytic; D012333:RNA, Messenger; D036781:Fimbriae Proteins; D004722:Endoribonucleases; D043244:Ribonuclease III; C468366:ribonuclease III, E coli; D043262:Ribonuclease P; C470865:ribonuclease P, E coli; C022537:ribonuclease E