title: Nucleotide sequence of a gene coding for a saliva-binding protein (SsaB) from Streptococcus sanguis 12 and possible role of the protein in coaggregation with actinomyces.
abstract: The nucleotide sequence of a 2.9-kb streptococcal DNA fragment which codes for two proteins with MrS of 36,000 (Streptococcus sanguis adhesin B [SsaB]) and 20,000 has been determined. The ssaB gene is 927 bp and codes for a 34,684-Da protein. The open reading frame coding for the 20-kDa protein is 489 bp and codes for a protein of 17,885 Da. The SsaB protein has a putative hydrophobic 19-amino-acid signal sequence resulting in a 32,620-Mr secreted protein, whereas the 20-kDa protein has no signal sequence. Both proteins are hydrophilic, and neither appears to have a hydrophobic membrane anchor sequence in the carboxy-terminal region. A DNA sequence homology of 73% exists between the cloned fragment containing the ssaB gene from S. sanguis 12 and the cloned fragment containing the type 1 fimbrial gene of S. sanguis FW213 (J.C. Fenno, D.J. LeBlanc, and P. Fives-Taylor, Infect. Immun. 57:3527-3533, 1989). Amino acid comparisons of the SsaB and type 1 fimbrial proteins show 87% homology, indicating a close similarity of the two proteins. Antiserum raised against the cloned SsaB protein cross-reacts with a 38-kDa protein identified from Streptococcus gordonii (S. sanguis) PK488 which was proposed to mediate coaggregation with Actinomyces naeslundii PK606 (P.E. Kolenbrander and R.N. Andersen, Infect. Immun. 58:3064-3072, 1990). The SsaB adhesion may play a role in oral colonization by binding either to a receptor on saliva or to a receptor on actinomyces.
authors.affiliation: Laboratory of Microbial Ecology, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: N
authors.initials: N
authors.lastname: Ganeshkumar
authors.forename: P M
authors.initials: PM
authors.lastname: Hannam
authors.forename: P E
authors.initials: PE
authors.lastname: Kolenbrander
authors.forename: B C
authors.initials: BC
authors.lastname: McBride
mesh_terms: D000190:Actinomyces / Q000378:metabolism*; D018829:Adhesins, Bacterial; D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D001483:Base Sequence; D003429:Cross Reactions / Q000276:immunology; D004269:DNA, Bacterial / Q000235:genetics; D010861:Fimbriae, Bacterial / Q000378:metabolism; D005798:Genes, Bacterial; D008074:Lipoproteins; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D011817:Rabbits; D012463:Saliva / Q000378:metabolism* / Q000382:microbiology; D012689:Sequence Homology, Nucleic Acid; D013298:Streptococcus sanguis / Q000235:genetics* / Q000378:metabolism
chemical_list: D018829:Adhesins, Bacterial; D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D008074:Lipoproteins; C067560:saliva-binding protein, Streptococcus sanguis 12