gbpC and pac gene mutations detected in Streptococcus mutans strain GS-5.
The Streptococcus mutans gbpC gene encoding cell wall-anchoring glucan-binding protein C is involved in the dextran(alpha-1,6 glucan)-dependent aggregation (ddag) of this organism. Unlike cells of other strains of S. mutans, strain GS-5 cells did not exhibit dextran(alpha-1,6 glucan)-dependent aggregation under any conditions. We therefore hypothesized that the gbpC gene may be mutated in strain GS-5. Sequencing analysis of the 1752-nucleotide GS-5 gbpC gene revealed a point mutation that switched codon 65 to a TAA termination codon. Strain GS-5 was previously reported also to have a mutation in the pac gene encoding the cell wall-anchored major protein antigen. The laboratory-maintained strain GS-5 is regarded as having lower cariogenicity than the original isolate. The decreased cariogenicity developed during the laboratory culture of strain GS-5 may have been caused by mutations in an environment lacking appropriate selective pressures.
Department of Biochemistry, Tokyo Dental College, 2-2, Masago 1-chome, Mihama-ku, Chiba City, 261-8502 Japan.
Y
Y
Sato
K
K
Okamoto
H
H
Kizaki
D000942:Antigens, Bacterial / Q000235:genetics*; D001422:Bacterial Adhesion / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D018389:Codon, Nonsense; D004252:DNA Mutational Analysis; D004269:DNA, Bacterial / Q000235:genetics; D016368:Frameshift Mutation; D005798:Genes, Bacterial; D037102:Lectins; D008562:Membrane Glycoproteins; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D017354:Point Mutation; D013295:Streptococcus mutans / Q000235:genetics*
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D002352:Carrier Proteins; D018389:Codon, Nonsense; D004269:DNA, Bacterial; D037102:Lectins; D008562:Membrane Glycoproteins; C055764:S-layer proteins; C037937:glucan-binding proteins