title: Chromosomal insertions and deletions in Streptococcus mutans.
abstract: Many isolates of Streptococcus mutans lack the ability to ferment melibiose and other sugars. We previously reported that this was commonly due to a chromosomal deletion and, in the present study, sequence information from the S. mutans genome project was used to design PCR primers to explore the nature and extent of the deletion. In all melibiose-negative strains examined, there was an incomplete insertion element, ISSmu3, in place of the 18-kb stretch of chromosome encoding the msm and GAL operons. Strains that were also unable to utilise beta-glucosides were found to have a separate 4 kb deletion in the BGL regulon that is proposed to be due to homologous recombination between two short stretches of identical sequence. The evidence is consistent with all the melibiose-negative strains examined being derived from a common ancestor.
authors.affiliation: Oral Biology, School of Dental Sciences, University of Newcastle, Newcastle upon Tyne, UK.
authors.forename: W G
authors.initials: WG
authors.lastname: Robinson
authors.forename: L A
authors.initials: LA
authors.lastname: Old
authors.forename: D S H
authors.initials: DS
authors.lastname: Shah
authors.forename: R R B
authors.initials: RR
authors.lastname: Russell
mesh_terms: D002872:Chromosome Deletion; D002876:Chromosomes, Bacterial / Q000235:genetics*; D004251:DNA Transposable Elements / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D005285:Fermentation / Q000235:genetics; D005690:Galactose / Q000235:genetics / Q000378:metabolism; D016680:Genome, Bacterial; D005960:Glucosides / Q000378:metabolism; D006801:Humans; D008553:Melibiose / Q000378:metabolism; D009876:Operon / Q000235:genetics; D018085:Regulon / Q000235:genetics; D017422:Sequence Analysis, DNA; D013295:Streptococcus mutans / Q000145:classification / Q000235:genetics*; D001617:beta-Glucosidase / Q000235:genetics
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D005960:Glucosides; D008553:Melibiose; D001617:beta-Glucosidase; D005690:Galactose