Our focus is the bacterial tad locus (tight adherence), a 14-gene cluster that directs synthesis of surface pili and is broadly conserved in Gram-negatives, Gram-positives, and Archaea. We discovered this locus in the Gram-negative pathogen Aggregatibacter actinomycetemcomitans, the causative agent of Localized Aggressive Periodontitis (LAP). Our prior studies have shown the tad locus is critical for A. actinomycetemcomitans surface adherence and pathogenicity. In this renewal application, we focus on two key proteins: Flp1, the pilin that mediates tight surface attachment, and TadZ, a tad-specific ATPase mimic that functions as a master localizer to recruit the Tad apparatus to the cell pole. These proteins are inviting therapeutic targets because they are either surface-accessible (Flp1) or have measurable molecular functions and interactions (TadZ). Our hypothesis is that functional perturbation of these proteins by genetic and chemical strategies will cause pilus defects that translate into loss of pathogenicity. We will pursue that hypothesis with three specific aims. First, we will manipulate the tad locus promoter in order to determine how overall tad expression levels affect pathogenicity. Second, we will define the TadZ properties that govern adherence and pathogenicity. Third, we will define Flp1 functional features that are required for pathogenicity. These studies will extend our current understanding of the A. actinomycetemcomitans tad locus function, based on in vitro assays, into critical tests of its biological function in colonization and virulence. In addition, our small-molecule screens may provide prospective lead compounds for development of new anti-infective agents, as well as molecular tools to facilitate inquiry into tad locus function in numerous other bacterial pathogens.

Public Health Relevance

We study a set of genes that govern infection in numerous bacteria. Our current goals are to understand how two key genes work to control infection, and to find chemicals that block their activity. These chemicals may be developed into new antibiotic drugs, supporting therapy for multiple types of infection.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Research Project (R01)
Project #
5R01DE014713-10
Application #
8299419
Study Section
Oral, Dental and Craniofacial Sciences Study Section (ODCS)
Program Officer
Lunsford, Dwayne
Project Start
2002-09-01
Project End
2013-08-31
Budget Start
2012-08-01
Budget End
2013-08-31
Support Year
10
Fiscal Year
2012
Total Cost
$382,523
Indirect Cost
$135,571
Name
Columbia University (N.Y.)
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
621889815
City
New York
State
NY
Country
United States
Zip Code
10032
Perez-Cheeks, Brenda A; Planet, Paul J; Sarkar, I Neil et al. (2012) The product of tadZ, a new member of the parA/minD superfamily, localizes to a pole in Aggregatibacter actinomycetemcomitans. Mol Microbiol 83:694-711
Clock, Sarah A; Planet, Paul J; Perez, Brenda A et al. (2008) Outer membrane components of the Tad (tight adherence) secreton of Aggregatibacter actinomycetemcomitans. J Bacteriol 190:980-90
Kram, Karin E; Hovel-Miner, Galadriel A; Tomich, Mladen et al. (2008) Transcriptional regulation of the tad locus in Aggregatibacter actinomycetemcomitans: a termination cascade. J Bacteriol 190:3859-68
Bhattacharjee, Mrinal K; Fine, Daniel H; Figurski, David H (2007) tfoX (sxy)-dependent transformation of Aggregatibacter (Actinobacillus) actinomycetemcomitans. Gene 399:53-64
Balashova, Nataliya V; Park, Diane H; Patel, Jigna K et al. (2007) Interaction between leukotoxin and Cu,Zn superoxide dismutase in Aggregatibacter actinomycetemcomitans. Infect Immun 75:4490-7
Perez, B A; Planet, P J; Kachlany, S C et al. (2006) Genetic analysis of the requirement for flp-2, tadV, and rcpB in Actinobacillus actinomycetemcomitans biofilm formation. J Bacteriol 188:6361-75
Tomich, Mladen; Fine, Daniel H; Figurski, David H (2006) The TadV protein of Actinobacillus actinomycetemcomitans is a novel aspartic acid prepilin peptidase required for maturation of the Flp1 pilin and TadE and TadF pseudopilins. J Bacteriol 188:6899-914