Actinobacillus actinomycetemcomitans and several pathogenic bacteria attach to abiotic surfaces and produce exopolymers that immobilize the bacterial cells on these colonized surfaces. Such colonization of these cells leads to biofilms with metabolic and physiological capabilities distinct from individual cells. Notable unique property of these biofilms is their resistance to antimicrobials. To colonize other virgin surfaces and to overcome starvation associated with overpopulation, cells must detach and disperse from these surfaces. We have previously shown that in Aa, the enzyme dispersin B is capable of assisting in the dispersal process. Additional studies by our group have shown that dispersin B is capable of preventing surface attachment of several related and non-related bacterial species. Since several pathogenic infections are caused by biofilms, new approaches in controlling the biofilm formation that focus on initial attachment of pathogenic bacteria on to the surfaces, in lieu of their antimicrobial resistance, are necessary. In this regard, study of enzymes that prevent the attachment of bacteria to surfaces through the use of extracellular polymeric substances is an underdeveloped area. We show that dispersin B depolymerizes exopolysaccharides that are made up of beta-1,6-linked N-acetylglucosamine (NAG), and is a potential candidate to remove biofilms of many Gram negative and Gram positive bacterial pathogens. Therefore, our long-range goals are to lay the foundation in the development of dispersin B as a broad spectrum anti-biofilm agent. Our immediate focus is on the structure-function studies on this enzyme to elucidate structural determinants that are necessary for its hydrolytic activity. We propose to achieve this through an integrated approach using x-ray crystallographic and mutational analysis.
The Specific Aims are: 1. Identify structural determinants governing the mechanism of action of dispersin B. 2. Map the substrate binding site through kinetic analysis using oligomeric substrate of beta-1,6-linked NAG. 3. Define the roles of specific amino acid residues in the enzymatic activity of dispersin B.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Research Project (R01)
Project #
5R01DE016291-03
Application #
7246661
Study Section
Oral, Dental and Craniofacial Sciences Study Section (ODCS)
Program Officer
Lunsford, Dwayne
Project Start
2005-07-15
Project End
2009-05-31
Budget Start
2007-07-01
Budget End
2009-05-31
Support Year
3
Fiscal Year
2007
Total Cost
$221,163
Indirect Cost
Name
University of Medicine & Dentistry of NJ
Department
Dentistry
Type
Schools of Dentistry
DUNS #
781265475
City
Newark
State
NJ
Country
United States
Zip Code
07101
Ragunath, C; DiFranco, K; Shanmugam, M et al. (2016) Surface display of Aggregatibacter actinomycetemcomitans autotransporter Aae and dispersin B hybrid act as antibiofilm agents. Mol Oral Microbiol 31:329-39
Fekete, Anikó; Borbás, Anikó; Gyémánt, Gyöngyi et al. (2011) Synthesis of ?-(1?6)-linked N-acetyl-D-glucosamine oligosaccharide substrates and their hydrolysis by Dispersin B. Carbohydr Res 346:1445-53
Izano, Era A; Sadovskaya, Irina; Wang, Hailin et al. (2008) Poly-N-acetylglucosamine mediates biofilm formation and detergent resistance in Aggregatibacter actinomycetemcomitans. Microb Pathog 44:52-60
Izano, Era A; Sadovskaya, Irina; Vinogradov, Evgeny et al. (2007) Poly-N-acetylglucosamine mediates biofilm formation and antibiotic resistance in Actinobacillus pleuropneumoniae. Microb Pathog 43:1-9
Manuel, Suba G A; Ragunath, Chandran; Sait, Hameetha B R et al. (2007) Role of active-site residues of dispersin B, a biofilm-releasing beta-hexosaminidase from a periodontal pathogen, in substrate hydrolysis. FEBS J 274:5987-99
Izano, E A; Wang, H; Ragunath, C et al. (2007) Detachment and killing of Aggregatibacter actinomycetemcomitans biofilms by dispersin B and SDS. J Dent Res 86:618-22