title: Running rings around RNA: a superfamily of phosphate-dependent RNases.
abstract: The exosome of Saccharomyces cerevisiae and the degradosome of Escherichia coli are multienzyme complexes involved in the degradation of mRNA. Both contain enzymes that are similar to the phosphate-dependent exoribonuclease RNase PH. These enzymes are phosphorylases that degrade RNA from the 3'-end. A recent X-ray crystallographic study of the polynucleotide phosphorylase (PNPase) from Streptomyces antibioticus reveals, for the first time, the atomic structure of a member of the RNase PH superfamily. Here, information from the structure of PNPase is used to address two related issues. First, the structure supports the idea that PNPase, which is a trimer of multidomain subunits, arose by duplication of a gene encoding an RNase PH-like enzyme. Second, the structure might explain how RNase PH-like enzymes associate into oligomeric rings that degrade RNA in a processive reaction.
authors.affiliation: Dept of Biochemistry, University of Cambridge, Cambridge, UK.
authors.forename: Martyn F
authors.initials: MF
authors.lastname: Symmons
authors.forename: Mark G
authors.initials: MG
authors.lastname: Williams
authors.forename: Ben F
authors.initials: BF
authors.lastname: Luisi
authors.forename: George H
authors.initials: GH
authors.lastname: Jones
authors.forename: Agamemnon J
authors.initials: AJ
authors.lastname: Carpousis
mesh_terms: D000595:Amino Acid Sequence; D004926:Escherichia coli / Q000201:enzymology*; D005095:Exoribonucleases / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D011117:Polyribonucleotide Nucleotidyltransferase / Q000737:chemistry*; D011487:Protein Conformation; D017510:Protein Folding; D012313:RNA / Q000737:chemistry*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid
chemical_list: D012313:RNA; C056502:ribonuclease PH; D011117:Polyribonucleotide Nucleotidyltransferase; D005095:Exoribonucleases