title: Turnover of mRNAs is one of the essential functions of RNase E.
abstract: RNase E is an essential bacterial endoribonuclease with a central role in processing tRNAs and rRNA, and turning over mRNAs. Previous studies in strains carrying mutations in the rne structural gene have shown that tRNA processing is likely to be an essential function of RNase E but have not determined whether mRNA turnover is also an essential function. To address this we selected extragenic suppressors of temperature-sensitive mutations in rne that cause a large increase in mRNA half-life at the non-permissive temperature. Fifteen suppressors were mapped to three different loci: relBE (toxin-antitoxin system); vacB (RNase R); and rpsA (ribosomal protein S1). Each suppressor class has the potential to interact with mRNA and each restores wild-type levels of mRNA turnover but does not reverse the minor defects in tRNA and rRNA processing. RelE toxin is especially interesting because its only known activity is to cleave mRNAs in the ribosomal A-site. The relBE suppressor mutations increase transcription of relE, and controlled overexpression of RelE alone was sufficient to suppress the rne ts phenotype. Suppression increased turnover of some major mRNAs (tufA, ompA) but not all mRNAs. We propose that turnover of some mRNAs is one of the essential functions of RNase E.
authors.affiliation: Department of Medical Biochemistry and Microbiology, The Biomedical Center (Box 582), Uppsala University, Uppsala, SE-751 23, Sweden.
authors.forename: Disa L
authors.initials: DL
authors.lastname: Hammarlöf
authors.affiliation: Department of Medical Biochemistry and Microbiology, The Biomedical Center (Box 582), Uppsala University, Uppsala, SE-751 23, Sweden.
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Bergman
authors.affiliation: Department of Medical Biochemistry and Microbiology, The Biomedical Center (Box 582), Uppsala University, Uppsala, SE-751 23, Sweden.
authors.forename: Eva
authors.initials: E
authors.lastname: Garmendia
authors.affiliation: Department of Medical Biochemistry and Microbiology, The Biomedical Center (Box 582), Uppsala University, Uppsala, SE-751 23, Sweden.
authors.forename: Diarmaid
authors.initials: D
authors.lastname: Hughes
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D004722:Endoribonucleases / Q000378:metabolism*; D005095:Exoribonucleases / Q000378:metabolism; D010641:Phenotype; D012323:RNA Processing, Post-Transcriptional; D012329:RNA, Bacterial / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000378:metabolism; D019779:Salmonella enterica / Q000235:genetics; D013489:Suppression, Genetic; D013696:Temperature
chemical_list: D001425:Bacterial Outer Membrane Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012335:RNA, Ribosomal; C078167:OMPA outer membrane proteins; D004722:Endoribonucleases; D005095:Exoribonucleases; C080868:ribonuclease R; C022537:ribonuclease E