title: Novobiocin-resistant mutants of Streptococcus sanguis with reduced cell hydrophobicity and defective in coaggregation.
abstract: Mutants of Streptococcus sanguis resistant to novobiocin (NovR-mutants) were isolated after mutagenesis of strain Challis with ethyl methanesulphonate. The resistance phenotype was transferred by DNA-mediated transformation back into the parent strain at high frequency suggesting resistance was due to mutation(s) in a single gene or in closely-linked genes. Cells of NovR-mutants had normal morphology and secreted similar proteins to the wild-type strain. However, mutant cultures had slower growth rates, the mutant cells had reduced hydrophobicity, and they showed a reduced degree of coaggregation with Actinomyces viscosus and Actinomyces naeslundii. Cell envelopes prepared from NovR-mutants differed from wild-type cell envelopes in that they (a) were impaired in ability to coaggregate with A. viscosus cells, and (b) had altered protein composition as detected by SDS-PAGE. The results suggest that hydrophobic proteins in the cell envelope of S. sanguis may be necessary for coaggregation of this bacterium with actinomycetes.
authors.affiliation: Department of Oral Biology and Oral Pathology, University of Otago, Dunedin, New Zealand.
authors.forename: H F
authors.initials: HF
authors.lastname: Jenkinson
mesh_terms: D001422:Bacterial Adhesion / Q000187:drug effects; D001426:Bacterial Proteins / Q000032:analysis; D004352:Drug Resistance, Microbial; D009154:Mutation; D009675:Novobiocin / Q000494:pharmacology*; D013298:Streptococcus sanguis / Q000187:drug effects*
chemical_list: D001426:Bacterial Proteins; D009675:Novobiocin