title: Ribonuclease P processes polycistronic tRNA transcripts in Escherichia coli independent of ribonuclease E.
abstract: The first step in the current model for the processing and maturation of mono- and polycistronic tRNA precursors in Escherichia coli involves initial cleavages by RNase E 1-3 nt downstream of each chromosomally encoded CCA determinant. Subsequently, each mature 5' terminus is generated by single RNase P cleavage, while the 3' terminus undergoes exonucleolytic processing by a combination of 3' --> 5' exonucleases. Here we describe for the first time a previously unidentified pathway for the maturation of tRNAs in polycistronic operons (valV valW and leuQ leuP leuV) where the processing of the primary transcripts is independent of RNase E. Rather, RNase P cleavages separate the individual tRNA precursors with the concomitant formation of their mature 5' termini. Furthermore, both polynucleotide phosphorylase (PNPase) and RNase II are required for the removal of the 3' Rho-dependent terminator sequences. Our data indicate that RNase P substrate recognition is more complex than previously envisioned.
authors.affiliation: Department of Genetics, University of Georgia, Athens, GA 30602, USA.
authors.forename: Bijoy K
authors.initials: BK
authors.lastname: Mohanty
authors.forename: Sidney R
authors.initials: SR
authors.lastname: Kushner
mesh_terms: D020121:5' Untranslated Regions / Q000737:chemistry / Q000378:metabolism; D004722:Endoribonucleases / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005095:Exoribonucleases / Q000378:metabolism; D008957:Models, Genetic; D009154:Mutation; D009876:Operon; D011117:Polyribonucleotide Nucleotidyltransferase / Q000378:metabolism; D012322:RNA Precursors / Q000737:chemistry / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D020871:RNA Stability; D012343:RNA, Transfer / Q000737:chemistry / Q000378:metabolism*; D012356:RNA, Transfer, Leu / Q000378:metabolism; D012366:RNA, Transfer, Val / Q000378:metabolism; D043262:Ribonuclease P / Q000235:genetics / Q000378:metabolism*; D013728:Terminator Regions, Genetic
chemical_list: D020121:5' Untranslated Regions; D029968:Escherichia coli Proteins; D012322:RNA Precursors; D012356:RNA, Transfer, Leu; D012366:RNA, Transfer, Val; D012343:RNA, Transfer; D011117:Polyribonucleotide Nucleotidyltransferase; D004722:Endoribonucleases; D005095:Exoribonucleases; C022535:exoribonuclease II; D043262:Ribonuclease P; C470865:ribonuclease P, E coli; C022537:ribonuclease E