title: Biochemical and genetic analysis of Streptococcus mutans alpha-galactosidase.
abstract: The aga gene coding for alpha-galactosidase in Streptococcus mutans was detected in a recombinant gene library constructed in phage lambda. The gene was subcloned into plasmid vectors and shown to specify a novel protein of Mr 80,000. Characterization of alpha-galactosidase from S. mutans and from recombinant Escherichia coli expressing aga indicated that the enzyme functions as a tetramer. The amino acid composition of the alpha-galactosidase, deduced from nucleotide sequencing of aga, gave a predicted Mr of 82,022 and revealed regions of homology to alpha-galactosidases encoded by the E. coli Raf plasmids and by Bacillus stearothermophilus. Inactivation of the aga gene in S. mutans resulted in loss of all alpha-galactosidase activity and abolished the ability to ferment melibiose; alpha-glucosidase activity was also lost, due to an indirect effect on the dexB gene.
authors.affiliation: Hunterian Dental Research Unit, London Hospital Medical College, UK.
authors.forename: J
authors.initials: J
authors.lastname: Aduse-Opoku
authors.forename: L
authors.initials: L
authors.lastname: Tao
authors.forename: J J
authors.initials: JJ
authors.lastname: Ferretti
authors.forename: R R
authors.initials: RR
authors.lastname: Russell
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial; D004591:Electrophoresis, Polyacrylamide Gel; D004790:Enzyme Induction; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D013295:Streptococcus mutans / Q000201:enzymology / Q000235:genetics*; D000519:alpha-Galactosidase / Q000235:genetics* / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D000519:alpha-Galactosidase