Organization and nucleotide sequence of the Streptococcus mutans galactose operon

Gene. 1996 Nov 21;180(1-2):137-44. doi: 10.1016/s0378-1119(96)00434-9.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Amino Acid Sequence
  • Base Sequence
  • Biological Transport, Active
  • Cloning, Molecular
  • DNA
  • Energy Metabolism
  • Escherichia coli / genetics
  • Galactose / genetics*
  • Galactose / metabolism
  • Gene Expression
  • Genetic Complementation Test
  • Molecular Sequence Data
  • Mutagenesis, Insertional
  • Operon*
  • Sequence Homology, Amino Acid
  • Streptococcus mutans / genetics*
  • Streptococcus mutans / metabolism


  • Adenosine Triphosphate
  • DNA
  • Galactose

Associated data

  • GENBANK/U21942