title: Sub-families of alpha/beta barrel enzymes: a new adenine deaminase family.
abstract: No gene coding for an adenine deaminase has been described in eukaryotes. However, physiological and genetical evidence indicates that adenine deaminases are present in the ascomycetes. We have cloned and characterised the genes coding for the adenine deaminases of Aspergillus nidulans, Saccharomyces cerevisiae and Schizosaccharomyces pombe. The A.nidulans gene was expressed in Escherichia coli and the purified enzyme shows adenine but not adenosine deaminase activity. The open reading frames coded by the three genes are very similar and obviously related to the bacterial and eukaryotic adenosine deaminases rather than to the bacterial adenine deaminases. The latter are related to allantoinases, ureases and dihydroorotases. The fungal adenine deaminases and the homologous adenosine deaminases differ in a number of residues, some of these being clearly involved in substrate specificity. Other prokaryotic enzymes in the database, while clearly related to the above, do not fit into either sub-class, and may even have a different specificity. These results imply that adenine deaminases have appeared twice in the course of evolution, from different ancestral enzymes constructed both around the alpha/beta barrel scaffold.
authors.affiliation: Institut de Génétique et Microbiologie, CNRS UMR 8621, Bâtiment 409, Université Paris XI, 91405 Orsay Cedex, France.
authors.forename: Carin
authors.initials: C
authors.lastname: Ribard
authors.forename: Michel
authors.initials: M
authors.lastname: Rochet
authors.forename: Bernard
authors.initials: B
authors.lastname: Labedan
authors.forename: Bertrand
authors.initials: B
authors.lastname: Daignan-Fornier
authors.forename: Pedro
authors.initials: P
authors.lastname: Alzari
authors.forename: Claudio
authors.initials: C
authors.lastname: Scazzocchio
authors.forename: Nathalie
authors.initials: N
authors.lastname: Oestreicher
mesh_terms: D000595:Amino Acid Sequence; D000619:Aminohydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D018076:DNA, Complementary; D005658:Fungi / Q000201:enzymology*; D008969:Molecular Sequence Data; D009154:Mutation; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D000619:Aminohydrolases; C018774:adenine deaminase