title: Organization and nucleotide sequence of the Streptococcus mutans galactose operon.
abstract: The galactose operon encoding a repressor and genes for the Leloir pathway for galactose metabolism (galactokinase, galactose-1-phosphate-uridyl transferase and UDP glucose-4-epimerase) was located adjacent to the multiple sugar metabolism (msm) operon on the chromosome of Streptococcus mutans Ingbritt (serotype c) and the complete nucleotide sequence of this 5-kilobase region was determined. The Leloir pathway was induced by the presence of galactose in the growth medium or following the release of intracellular galactose after uptake and cleavage of alpha-galactosides by the multiple sugar metabolism system. Analysis of the mechanism of galactose transport confirmed the absence of a galactose-specific phosphotransferase system and suggested the presence of an inducible galactose permease. Evidence is presented that galactose transport is independent of the proton motive force and may be ATP-dependent.
authors.affiliation: Department of Microbiology and Immunology, University of Oklahoma, Oklahoma City 73104, USA.
authors.forename: D
authors.initials: D
authors.lastname: Ajdić
authors.forename: I C
authors.initials: IC
authors.lastname: Sutcliffe
authors.forename: R R
authors.initials: RR
authors.lastname: Russell
authors.forename: J J
authors.initials: JJ
authors.lastname: Ferretti
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D001693:Biological Transport, Active; D003001:Cloning, Molecular; D004247:DNA; D004734:Energy Metabolism; D004926:Escherichia coli / Q000235:genetics; D005690:Galactose / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009876:Operon; D017386:Sequence Homology, Amino Acid; D013295:Streptococcus mutans / Q000235:genetics* / Q000378:metabolism
chemical_list: D000255:Adenosine Triphosphate; D004247:DNA; D005690:Galactose