title: Developing structure-based models to predict substrate specificity of D-group (Type II) molybdenum enzymes: application to a molybdo-enzyme of unknown function from Archaeoglobus fulgidus.
abstract: The AF0174-AF0176 gene cluster in Archaeoglobus fulgidus encodes a putative oxyanion reductase of the D-type (Type II) family of molybdo-enzymes. Sequence analysis reveals that the catalytic subunit AF0176 shares low identity (31-32%) and similarity (41-42%) to both NarG and SerA, the catalytic components of the respiratory nitrate and selenate reductases respectively. Consequently, predicting the oxyanion substrate selectivity of AF0176 has proved difficult based solely on sequence alignments. In the present study, we have modelled both AF0176 and SerA on the recently determined X-ray structure of the NAR (nitrate reductase) from Escherichia coli and have identified a number of key amino acid residues, conserved in all known NAR sequences, including AF0176, that we speculate may enhance selectivity towards trigonal planar (NO(3)(-)) rather than tetrahedral (SeO(4)(2-) and ClO(4)(-)) substrates.
authors.affiliation: Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne NE2 4HH, UK.
authors.forename: E J
authors.initials: EJ
authors.lastname: Dridge
authors.forename: D J
authors.initials: DJ
authors.lastname: Richardson
authors.forename: R J
authors.initials: RJ
authors.lastname: Lewis
authors.forename: C S
authors.initials: CS
authors.lastname: Butler
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019611:Archaeoglobus fulgidus / Q000201:enzymology* / Q000235:genetics; D001665:Binding Sites; D003067:Coenzymes; D008667:Metalloproteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D000090006:Molybdenum Cofactors; D005810:Multigene Family; D009942:Organometallic Compounds / Q000378:metabolism*; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D011621:Pteridines / Q000378:metabolism*; D016415:Sequence Alignment; D013379:Substrate Specificity; D014414:Tungsten / Q000737:chemistry
chemical_list: D019843:Archaeal Proteins; D003067:Coenzymes; D008667:Metalloproteins; D000090006:Molybdenum Cofactors; D009942:Organometallic Compounds; D010088:Oxidoreductases; D011621:Pteridines; D014414:Tungsten; C022261:molybdopterin