title: The genome of Streptococcus mitis B6--what is a commensal?
abstract: Streptococcus mitis is the closest relative of the major human pathogen S. pneumoniae. The 2,15 Mb sequence of the Streptococcus mitis B6 chromosome, an unusually high-level beta-lactam resistant and multiple antibiotic resistant strain, has now been determined to encode 2100 genes. The accessory genome is estimated to represent over 40%, including 75 mostly novel transposases and IS, the prophage phiB6 and another seven phage related regions. Tetracycline resistance mediated by Tn5801, and an unusual and large gene cluster containing three aminoglycoside resistance determinants have not been described in other Streptococcus spp. Comparative genomic analyses including hybridization experiments on a S. mitis B6 specific microarray reveal that individual S. mitis strains are almost as distantly related to the B6 strain as S. pneumoniae. Both species share a core of over 900 genes. Most proteins described as pneumococcal virulence factors are present in S. mitis B6, but the three choline binding proteins PcpA, PspA and PspC, and three gene clusters containing the hyaluronidase gene, ply and lytA, and the capsular genes are absent in S. mitis B6 and other S. mitis as well and confirm their importance for the pathogenetic potential of S. pneumoniae. Despite the close relatedness between the two species, the S. mitis B6 genome reveals a striking X-alignment when compared with S. pneumoniae.
authors.affiliation: Department of Microbiology, University of Kaiserslautern, Kaiserslautern, Germany.
authors.forename: Dalia
authors.initials: D
authors.lastname: Denapaite
authors.forename: Reinhold
authors.initials: R
authors.lastname: Brückner
authors.forename: Michael
authors.initials: M
authors.lastname: Nuhn
authors.forename: Peter
authors.initials: P
authors.lastname: Reichmann
authors.forename: Bernhard
authors.initials: B
authors.lastname: Henrich
authors.forename: Patrick
authors.initials: P
authors.lastname: Maurer
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Schähle
authors.forename: Peter
authors.initials: P
authors.lastname: Selbmann
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Zimmermann
authors.forename: Rolf
authors.initials: R
authors.lastname: Wambutt
authors.forename: Regine
authors.initials: R
authors.lastname: Hakenbeck
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial / Q000235:genetics*; D055028:Comparative Genomic Hybridization; D004251:DNA Transposable Elements / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics*; D016680:Genome, Bacterial / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D034361:Streptococcus mitis / Q000145:classification / Q000235:genetics*; D013296:Streptococcus pneumoniae / Q000235:genetics; D026801:Synteny; D037521:Virulence Factors / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D037521:Virulence Factors