Genome sequence of Streptococcus mutans UA159, a cariogenic dental pathogen

Abstract

Streptococcus mutans is the leading cause of dental caries (tooth decay) worldwide and is considered to be the most cariogenic of all of the oral streptococci. The genome of S. mutans UA159, a serotype c strain, has been completely sequenced and is composed of 2,030,936 base pairs. It contains 1,963 ORFs, 63% of which have been assigned putative functions. The genome analysis provides further insight into how S. mutans has adapted to surviving the oral environment through resource acquisition, defense against host factors, and use of gene products that maintain its niche against microbial competitors. S. mutans metabolizes a wide variety of carbohydrates via nonoxidative pathways, and all of these pathways have been identified, along with the associated transport systems whose genes account for almost 15% of the genome. Virulence genes associated with extracellular adherent glucan production, adhesins, acid tolerance, proteases, and putative hemolysins have been identified. Strain UA159 is naturally competent and contains all of the genes essential for competence and quorum sensing. Mobile genetic elements in the form of IS elements and transposons are prominent in the genome and include a previously uncharacterized conjugative transposon and a composite transposon containing genes for the synthesis of antibiotics of the gramicidin͞bacitracin family; however, no bacteriophage genomes are present.

Complete sequence and comparative genome analysis of the dairy bacterium Streptococcus thermophilus

“…The ability to use an extended range of carbohydrates is reported to be important for the virulence of pathogenic streptococci, possibly by allowing maintenance of these bacteria in their ecological niche 5,9 . The observed impairment of this function in S. thermophilus is likely to reduce the virulence potential.…”

“…The dairy streptococcus must have followed a divergent evolutionary path from that of its pathogenic congeners, as it has adapted to a rather narrow, well-defined and constant ecological niche, milk. To obtain insight into this path and to assess the potential for virulence of this bacterium, we sequenced the genomes of two yogurt strains of S. thermophilus, and compared them to those of previously sequenced pathogenic streptococci [4][5][6][7][8][9] .…”

Four gbpC Gene Homologues in Streptococcus sobrinus

“…In addition, the genome project of this organism revealed the absence of other gbpC gene homologues 11) . The S. sobrinus genome contained at least four gbpC gene homologues presumed to be duplicated from their antecedent genes in contrast to S. mutans genome.…”

Inactivation of a gene for a fibronectin-binding protein of the oral bacterium Streptococcus mutans partially impairs its adherence to fibronectin

“…The DNA sequence for a putative fibronectin-binding protein of S. mutans was obtained from a BLAST search of the S. mutans genome sequence ( [25]; GenBank accession no. AE014133).…”

“…For stable expression of the histidine tagged SmFnB protein, plasmid pQE31(SmFnB) was transformed into E. coli M15 (pREP4) cells. The S. mutans fibronectin-binding protein that we have designated SmFnB is assigned the name SMU.1449 in the published S. mutans genomic sequence [25].…”