title: An important role for RNase R in mRNA decay.
abstract: mRNA decay is a major determinant of gene expression. In Escherichia coli, message degradation initiates with an endoribonucleolytic cleavage followed by exoribonuclease digestion to generate 5'-mononucleotides. Although the 3' to 5' processive exoribonucleases, PNPase and RNase II, have long been considered to be mediators of this digestion, we show here that another enzyme, RNase R, also participates in the process. RNase R is particularly important for removing mRNA fragments with extensive secondary structure, such as those derived from the many mRNAs that contain REP elements. In the absence of RNase R and PNPase, REP-containing fragments accumulate to high levels. RNase R is unusual among exoribonucleases in that, by itself, it can digest through extensive secondary structure provided that a single-stranded binding region, such as a poly(A) tail, is present. These data demonstrate that RNase R, which is widespread in prokaryotes and eukaryotes, is an important participant in mRNA decay.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, Miami, FL 33101, USA.
authors.forename: Zhuan-Fen
authors.initials: ZF
authors.lastname: Cheng
authors.forename: Murray P
authors.initials: MP
authors.lastname: Deutscher
mesh_terms: D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism*; D005095:Exoribonucleases / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000235:genetics / Q000378:metabolism; D026723:Polyadenylation; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D009841:Oligonucleotides; D012333:RNA, Messenger; C489683:rnr protein, E coli; D005095:Exoribonucleases