title: Linkage of catalysis and 5' end recognition in ribonuclease RNase J.
abstract: In diverse bacterial species, the turnover and processing of many RNAs is mediated by the ribonuclease RNase J, a member of the widely occurring metallo-β-lactamase enzyme family. We present crystal structures of Streptomyces coelicolor RNase J with bound RNA in pre- and post-cleavage states, at 2.27 Å and 2.80 Å resolution, respectively. These structures reveal snapshots of the enzyme cleaving substrate directionally and sequentially from the 5' terminus. In the pre-cleavage state, a water molecule is coordinated to a zinc ion pair in the active site but is imperfectly oriented to launch a nucleophilic attack on the phosphate backbone. A conformational switch is envisaged that enables the in-line positioning of the attacking water and may be facilitated by magnesium ions. Adjacent to the scissile bond, four bases are stacked in a tightly sandwiching pocket, and mutagenesis results indicate that this organization helps to drive processive exo-ribonucleolytic cleavage. Like its numerous homologues, S. coelicolor RNase J can also cleave some RNA internally, and the structural data suggest how the preference for exo- versus endo-cleavage mode is linked with recognition of the chemical status of the substrate's 5' end.
authors.affiliation: Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK.
authors.forename: Xue-Yuan
authors.initials: XY
authors.lastname: Pei
authors.affiliation: Department of Biology, Emory University, Atlanta Georgia, USA.
authors.forename: Patricia
authors.initials: P
authors.lastname: Bralley
authors.affiliation: Department of Biology, Emory University, Atlanta Georgia, USA bfl20@cam.ac.uk.
authors.forename: George H
authors.initials: GH
authors.lastname: Jones
authors.affiliation: Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK bfl20@cam.ac.uk.
authors.forename: Ben F
authors.initials: BF
authors.lastname: Luisi
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D055162:Biocatalysis; D020134:Catalytic Domain; D008958:Models, Molecular; D009154:Mutation; D011485:Protein Binding; D055503:Protein Multimerization; D012313:RNA / Q000737:chemistry; D059367:RNA Cleavage; D012260:Ribonucleases / Q000737:chemistry* / Q000235:genetics; D048372:Streptomyces coelicolor / Q000201:enzymology
chemical_list: D001426:Bacterial Proteins; D012313:RNA; D012260:Ribonucleases