The focus of our research program is to understand the role of coaggregation in bacterial accretion of early colonizing bacteria on a clean tooth surface. The primary colonizers include actinomyces and streptococci. The 34.8-kDa lipoprotein surface-adhesin, ScaA, from Streptococcus gordonii ATCC 51656 is encoded as part of a 2.5 kb transcription unit consisting of three genes. This unit is a putative ATP-binding cassette operon similar to the operons encoding the binding-protein dependent transport systems of Gram-negative bacteria and the binding lipoprotein dependent transport systems of Gram-positive bacteria. ScaA probably is anchored in the cell membrane through its lipid moiety, while its receptor-recognizing binding site is exposed to the environment. Two coaggregation-relevant genes in Streptococcus gordonii DL1 have been identified by transposon mutagenesis and by integrative mutagenesis. By sequencing the DNA flanking the transposon, a close relationship was found to genes involved with synthesis of lipoteichoic acids, another class of surface molecules. The sequence flanking the erythromycin insertion plasmid is 56% identical to a 34- kDa protein from Bacillus subtilis. The insertion mutants of S. gordonii DL1 have lost a 100-kDa protein from their surface. This gene has been cloned and transformants regained the parental phenotype and the 100-kDa protein. It is proposed that the protein is an adhesin mediating intrageneric coaggregation. Actinomyces serovar WVA963 strain PK1259 exhibits only lactose-inhibitable coaggregation with streptococci. One of the spontaneous coaggregation defective mutants isolated excretes a 95-kDa protein that has been purified by lactose-agarose affinity beads and by binding to the partner streptococcal cells. Antiserum to the lactose-agarose bead preparation blocks coaggregation of the parent actinomyces with streptococci, suggesting that the 95-kDa protein is the adhesin mediating this coaggregation. The long range goal of these studies, collectively, is to elucidate the molecular mechanisms responsible for bacterial colonization in the human oral ecosystem.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Intramural Research (Z01)
Project #
1Z01DE000273-18
Application #
2572288
Study Section
Special Emphasis Panel (LME)
Project Start
Project End
Budget Start
Budget End
Support Year
18
Fiscal Year
1996
Total Cost
Indirect Cost
Name
National Institute of Dental & Craniofacial Research
Department
Type
DUNS #
City
State
Country
United States
Zip Code
Periasamy, Saravanan; Kolenbrander, Paul E (2009) Aggregatibacter actinomycetemcomitans builds mutualistic biofilm communities with Fusobacterium nucleatum and Veillonella species in saliva. Infect Immun 77:3542-51
Periasamy, Saravanan; Chalmers, Natalia I; Du-Thumm, Laurence et al. (2009) Fusobacterium nucleatum ATCC 10953 requires Actinomyces naeslundii ATCC 43146 for growth on saliva in a three-species community that includes Streptococcus oralis 34. Appl Environ Microbiol 75:3250-7
Jakubovics, Nicholas S; Gill, Steven R; Iobst, Stacey E et al. (2008) Regulation of gene expression in a mixed-genus community: stabilized arginine biosynthesis in Streptococcus gordonii by coaggregation with Actinomyces naeslundii. J Bacteriol 190:3646-57
Bachrach, Gilad; Altman, Hamutal; Kolenbrander, Paul E et al. (2008) Resistance of Porphyromonas gingivalis ATCC 33277 to direct killing by antimicrobial peptides is protease independent. Antimicrob Agents Chemother 52:638-42
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Diaz, Patricia I; Chalmers, Natalia I; Rickard, Alexander H et al. (2006) Molecular characterization of subject-specific oral microflora during initial colonization of enamel. Appl Environ Microbiol 72:2837-48
Kolenbrander, Paul E; Palmer Jr, Robert J; Rickard, Alexander H et al. (2006) Bacterial interactions and successions during plaque development. Periodontol 2000 42:47-79
Rickard, Alexander H; Palmer Jr, Robert J; Blehert, David S et al. (2006) Autoinducer 2: a concentration-dependent signal for mutualistic bacterial biofilm growth. Mol Microbiol 60:1446-56
Diaz, Patricia I; Slakeski, Nada; Reynolds, Eric C et al. (2006) Role of oxyR in the oral anaerobe Porphyromonas gingivalis. J Bacteriol 188:2454-62

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