Cleavage by RNase III in the transcripts of the met Y-nus-A-infB operon of Escherichia coli releases the tRNA and initiates the decay of the downstream mRNA.
The metY gene coding for a minor form of the initiator tRNA is the first gene of a complex polycistronic operon also encoding the transcription termination factor NusA and the translation initiation factor IF2. The mixed tRNA-mRNA polycistronic transcript is cleaved by RNase III in a hairpin structure downstream from the tRNA. This cleavage separates the tRNA from the mRNA and initiates the rapid degradation of the 5' extremity of the downstream mRNA. Dissociation of the structural (tRNA) and informational (mRNA) RNAs from this operon is also achieved by independent transcription in vivo. The presence of two transcription terminators located downstream from metY produces a small tRNAMetf2 precursor transcript, whereas an internal promoter situated between metY and the first open reading frame directs the transcription of only the protein-coding part of the operon.
Régnier
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Institut de Biologie Physico Chimique, Paris, France.
Grunberg-Manago
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D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D004722:Endoribonucleases / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D006860:Hydrogen Bonding; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009876:Operon; D010448:Peptide Initiation Factors / Q000235:genetics; D011401:Promoter Regions, Genetic; D012323:RNA Processing, Post-Transcriptional; D012329:RNA, Bacterial / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D012345:RNA, Transfer, Amino Acid-Specific / Q000235:genetics*; D012358:RNA, Transfer, Met / Q000235:genetics* / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D043244:Ribonuclease III; D013728:Terminator Regions, Genetic; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D010448:Peptide Initiation Factors; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012345:RNA, Transfer, Amino Acid-Specific; D012358:RNA, Transfer, Met; D004722:Endoribonucleases; D043244:Ribonuclease III; C468366:ribonuclease III, E coli