It is well known that salivary components can interact with microbes to influence their colonization of the oral cavity. One such interaction involves the abundant salivary enzyme, amylase, which binds specifically and with high affinity to commensal oral streptococci that are early colonizers of the saliva-coated tooth and numerous in supragingival dental plaque. Amylase-binding streptococci (ABS) colonize only hosts with detectable salivary amylase activity suggesting that amylase interactions modulate oral colonization by ABS and have an evolutionary basis. The ABS S. gordonii produces two amylase-binding proteins (ABPs) [AbpA (20-kDa) and AbpB (82-kDa) of Streptococcus gordonii. The binding of amylase to this species is dependent only on AbpA in S. gordonii (and likely its homologs in other species), and not on AbpB. In vitro studies found ABPs to play a role in bacterial adhesion and biofilm formation. Interestingly, AbpA defective S. gordonii mutants were able to colonize rat mouths as well as the parental strains, suggesting that additional bacterial factors are involved in colonization and survival in vivo. In light of these findings, we have considered potentially novel functions for these proteins. Preliminary studies suggest that amylase-binding to S. gordonii elicits differential gene expression in the bacterial cell. Thus, th Specific Aims of this proposal are to: 1: identify streptococcal components that interact with AbpA that may participate in a novel signaling pathway. 2: determine the three-dimensional structure of AbpA, identify amylase binding motifs and to address the evolutionary basis for the divergence of ABP gene sequence. 3: compare the global gene expression response of S. gordonii following binding of amylase to the response induced by the binding of whole- and ductal-saliva and other purified salivary components (such as mucins, sIgA, etc). Knowledge of saliva-mediated bacterial signaling pathways could have clinical application, for example by devising analog agents that serve as inhibitors or promoters of microbial colonization. Such agents may enable selective manipulation of bacterial colonization, and by extension, impact disease prevention or control. This knowledge could well extend beyond biofilm development in the oral cavity, with application to other microbial communities affecting systemic disease.

Public Health Relevance

Components of saliva are thought to contribute to the formation of dental plaque, the biofilm that forms on teeth that causes dental decay and gum disease. This proposal will address details of the mechanism by which an abundant enzyme in saliva, amylase, interacts with a common oral organism, Streptococcus gordonii and the function of this interaction. Understanding of this interaction could lead to new strategies to control dental plaque formation and thus prevent oral disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Research Project (R01)
Project #
3R01DE022673-02S1
Application #
8711690
Study Section
Oral, Dental and Craniofacial Sciences Study Section (ODCS)
Program Officer
Lunsford, Dwayne
Project Start
2012-05-04
Project End
2015-08-31
Budget Start
2013-09-01
Budget End
2014-04-30
Support Year
2
Fiscal Year
2013
Total Cost
$219,350
Indirect Cost
$81,394
Name
State University of New York at Buffalo
Department
Dentistry
Type
Schools of Dentistry
DUNS #
038633251
City
Buffalo
State
NY
Country
United States
Zip Code
14260