Insertional inactivation of the Streptococcus mutans dexA (dextranase) gene results in altered adherence and dextran catabolism

Article Abstract:

Streptococcus mutans LT11 cells containing an inactive dextranase gene (dexA) show greater adherence to smooth surfaces than the wild-type cells. The dexA and dexB mutants, which encodes dextran glucosidase, are unable to ferment dextran. The morphology of the mutant colonies is different due to an increase in the amount of polymers and 1,6-alpha-linked glucosyl amino acids. Aggregation of cells in the presence of sucrose is unaffected in the mutants. The dexA gene is inactivated by inserting the Escherichia coli pVA891 vector containing S. mutans chromosome fragments into the S. mutans LT11 cells.

Mutation (Biology), Mutation, Cell adhesion

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Expression of Streptococcus mutans fimA is iron-responsive and regulated by a DtxR homologue

Article Abstract:

Expression of Streptococcus mutans fimA has been found to be responsive to iron and regulated by a DtxR homologue. S. mutans is the main causative agent of human dental cavities. Cloning of the S. mutans fimA homologue led to construction of a fimA knockout mutant. The mutant did not grow well in an iron-limiting medium vs the growth of the wild-type progenitor strain. This lends support to the hypothesis that FimA has a role in S. mutans iron transport, as do other findings.

United States, Statistical Data Included, Usage, Causes of, Dental caries, Cloning, Iron, Iron (Metal)

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Characterization of a copper-transport operon, copYAZ, from Streptococcus mutans

Article Abstract:

Results demonstrate that three genes comprise the copper-transport operon copYAZ in streptococcus mutans JH1005 with encoded proteins exhibiting heavy metal-binding activities. The operon is specific for copper as shown by cop knock-out mutant analysis.

Canada, Biological transport, Operons, Copper, Copper (Nutrient), Bioavailability

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