title: Structure and activity of a novel archaeal β-CASP protein with N-terminal KH domains.
abstract: MTH1203, a β-CASP metallo-β-lactamase family nuclease from the archaeon Methanothermobacter thermautotrophicus, was identified as a putative nuclease that might contribute to RNA processing. The crystal structure of MTH1203 reveals that, in addition to the metallo-β-lactamase nuclease and the β-CASP domains, it contains two contiguous KH domains that are unique to MTH1203 and its orthologs. RNA-binding experiments indicate that MTH1203 preferentially binds U-rich sequences with a dissociation constant in the micromolar range. In vitro nuclease activity assays demonstrated that MTH1203 is a zinc-dependent nuclease. MTH1203 is also shown to be a dimer and, significantly, this dimerization enhances the nuclease activity. Transcription termination in archaea produces mRNA transcripts with U-rich 3' ends that could be degraded by MTH1203 considering its RNA-binding specificity. We hypothesize that this nuclease degrades mRNAs of proteins targeted for degradation and so regulates archaeal RNA turnover, possibly in concert with the exosome.
authors.affiliation: York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5YW, United Kingdom.
authors.forename: Ana P G
authors.initials: AP
authors.lastname: Silva
authors.forename: Maria
authors.initials: M
authors.lastname: Chechik
authors.forename: Robert T
authors.initials: RT
authors.lastname: Byrne
authors.forename: David G
authors.initials: DG
authors.lastname: Waterman
authors.forename: C Leong
authors.initials: CL
authors.lastname: Ng
authors.forename: Eleanor J
authors.initials: EJ
authors.lastname: Dodson
authors.forename: Eugene V
authors.initials: EV
authors.lastname: Koonin
authors.forename: Alfred A
authors.initials: AA
authors.lastname: Antson
authors.forename: Callum
authors.initials: C
authors.lastname: Smits
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D019281:Dimerization; D004926:Escherichia coli; D005092:Exonucleases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D017013:Methanobacteriaceae / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D015032:Zinc / Q000378:metabolism; D001618:beta-Lactamases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D019843:Archaeal Proteins; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D005092:Exonucleases; C026919:nuclease beta; D001618:beta-Lactamases; D015032:Zinc