title: Dispensable genes and foreign DNA in Streptococcus mutans.
abstract: A range of properties, including the ability to utilize various sugars, bind macromolecules and produce mutacins, are known to vary in their occurrence in different strains of Streptococcus mutans. In addition, insertion-sequence elements show a limited distribution and sequencing of the genome of S. mutans UA159 has revealed the presence of putative genomic islands of atypical base composition indicative of foreign DNA. PCR primers flanking regions suspected of having inserted DNA were designed on the basis of the genome sequence of S. mutans UA159 and used to explore variation in a collection of 39 strains isolated in various parts of the world over the last 40 years. Extensive differences between strains were detected, and similar insertion/deletion events appear to be present in the genomes of strains with very different origins. In two instances, insertion of foreign DNA appears to have displaced original S. mutans genes. Together with previous results on the occurrence of deletions in genes associated with sugar metabolism, the results indicate that S. mutans has a core genome and a dispensable genome, and that dispensable genes have become widely distributed through horizontal transfer.
authors.affiliation: Oral Biology, School of Dental Sciences, University of Newcastle, Newcastle upon Tyne NE2 4BW, UK.
authors.forename: Janet C
authors.initials: JC
authors.lastname: Waterhouse
authors.affiliation: Oral Biology, School of Dental Sciences, University of Newcastle, Newcastle upon Tyne NE2 4BW, UK.
authors.forename: Roy R B
authors.initials: RRB
authors.lastname: Russell
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000032:analysis; D017353:Gene Deletion; D005798:Genes, Bacterial; D014644:Genetic Variation; D044404:Genomic Islands; D006801:Humans; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D013295:Streptococcus mutans / Q000145:classification* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial