Chromosomal deletions in melibiose-negative isolates of Streptococcus mutans

J Dent Res. 1991 Nov;70(11):1422-6. doi: 10.1177/00220345910700110501.

Abstract

Isolates from a collection of phenotypically melibiose-negative (Mel-) Streptococcus mutans from widely-scattered geographical locations were examined and found to lack the activities of the enzymes alpha-galactosidase and alpha-glucosidase, in addition to being unable to transport melibiose. Cloned fragments of S. mutans DNA from the region of the chromosome carrying the genes for alpha-galactosidase (aga), sucrose phosphorylase (gtfA), and dextran glucosidase (dexB), as well as the genes encoding components of the binding-protein-dependent uptake system for raffinose and melibiose, were used in hybridization studies for investigation of the genetic basis of the Mel-phenotype. A region of at least 12 kilobases, containing all the above genes, was found to be deleted from the chromosome of the Mel- strains. It appears that this region of the chromosome is not essential for survival of S. mutants in the oral cavity. The reason for the frequent occurrence of deletions, as opposed to other forms of mutational events, is unknown.

Publication types

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

MeSH terms

  • Biological Transport
  • Chromosome Deletion*
  • DNA, Bacterial / analysis
  • Enzyme Induction
  • Galactosidases / metabolism
  • Glucosidases / metabolism
  • Glucosyltransferases / metabolism
  • Immunoblotting
  • Melibiose / metabolism*
  • Nucleic Acid Hybridization
  • Streptococcus mutans / enzymology*
  • Streptococcus mutans / genetics
  • Streptococcus mutans / isolation & purification

Substances

  • DNA, Bacterial
  • Melibiose
  • Glucosyltransferases
  • sucrose phosphorylase
  • Galactosidases
  • Glucosidases
  • exo-1,6-alpha-glucosidase