Microbiology, Immunology & Molecular Genetics Faculty
David J. Kolodrubetz, Ph.D.
The underlying theme of Dr. Kolodrubetz' lab's research efforts has been to develop and use molecular genetic, genomic and biochemical approaches to elucidate the functions and regulation of virulence factors in periodontal pathogens.
The lab's studies with Aggregatibacter actinomycetemcomitans (Aa) have mainly focused on leukotoxin, a virulence protein that helps the bacterium evade the host innate immune response. They have used comprehensive biochemical and genetic approaches to identify and characterize three DNA binding proteins that work together in a novel pathway to accurately regulate leukotoxin transcription in Aa. Microarray analyses have shown that these three transcription factors are global regulators, altering the synthesis of hundreds of genes (regulons) in Aa. Because “networking” is a critical concept in regulatory pathways, they are using whole genome technologies to determine how these three global regulatory proteins coordinate their activities to control the expression of multiple virulence genes in Aa.
More recently, Dr. Kolodrubetz' lab has started a project based upon the observation that dozens of mRNAs are mis-regulated in a protein-deacetylase mutant of A. actinomycetemcomitans. Genetics, mass spectrometry and RNA-Seq are being used to prove our hypothesis that lysine de-acetylation of transcription factors by the deacetylase CobB plays a key role in modulating the transcription profile of Aa. Importantly, since CobB is an NAD+-dependent deacetylase, our results would also suggest that there is an interesting new connection between physiology (NAD levels) and transcriptional regulation (acetylation) in bacteria.
Finally, the lab has a long-standing collaboration with Dr. Larry Chu (Developmental Dentistry) investigating the pathogenic potential of the glutathione catabolic pathway in T. denticola. They have constructed a T. denticola mutant that cannot metabolize glutathione to H2S and are using it in in vitro assays and in a rat model of alveolar bone loss to test the hypothesis that a decrease in glutathione levels by T. denticola metabolism and the accompanying increase in H2S production will play key roles in periodontal disease pathology. Re-establishing normal periodontal pocket thiol-molecule homeostasis by inhibiting a bacterial catabolic pathway pharmacologically could be an innovative strategy to reduce host damage in periodontitis.
Awards & Accomplishments
- Recipient, Dean‘s Award for Exceptional Graduate Teaching, 2004
- American Society for Microbiology
- International Association for Dental Research
- American Dental Education Association
Kruppa, M., R.D. Moir, D. Kolodrubetz and I.M. Willis. 2001. Nhp6, an HMG1 protein, functions in SNR6 transcription by RNA polymerase III in S. cerevisiae. Molecular Cell. 7:309-318. PMID 11239460
Xu, X., S.C. Holt and D. Kolodrubetz. 2001. Cloning and expression of two novel hemin binding protein genes from Treponema denticola. Infection and Immunity. 69:4465-4472. PMC98520
Kolodrubetz, D., M. Kruppa and A. Burgum. 2001. Gene dosage affects the expression of the duplicated NHP6 genes of S. cerevisiae. Gene. 272:93-101. PMID 11470514
Xu, X., and D. Kolodrubetz. 2002. Construction and analysis of hemin binding protein mutants in the oral pathogen Treponema denticola. Res. in Microbiology. 153:569-577. PMID12455704
Kolodrubetz, D., L. Phillips, C. Jacobs, A. Burgum, and E. Kraig. 2003. Anaerobic regulation of A. actinomycetemcomitans leukotoxin transcription is ArcA/FnrA-independent and requires a novel promoter element. Res. in Microbiology. 154:645-653. PMID 14596902
Lawley, G.R., Schindler, W.G., Walker III, W.A., and D. Kolodrubetz. 2004. Evaluation of ultrasonically placed MTA and fracture resistance with intracanal composite resin in a model of apexification. Journal of Endodontics. 30:167-172. PMID 15055436
Chu, L., Lai, Y., Xu, X., Eddy, S., Yang, S., Song, L. and D. Kolodrubetz. 2008. A 52-kDa leucyl aminopeptidase from Treponema denticola is a cysteinylglycinase that mediates the second step of glutathione metabolism. J. Biol. Chem. 283:19351-19358. PMC2443665
Kolodrubetz, D., L. Phillips, and A. Burgum. 2010. Repression of aerobic leukotoxin transcription by integration host factor (IHF) in A. actinomycetemcomitans. Res. in Microbiology. 161:541-548. PMID: 20493253
Feuerbacher, L.A., A. Burgum, and D. Kolodrubetz. 2011. The cyclic-AMP receptor protein (CRP) regulon in Aggregatibacter actinomycetemcomitans includes leukotoxin. Microb. Path. 51:133-141. PMID:21575705.
Childress, C., L.A. Feuerbacher, L. Phillips, A. Burgum, and D. Kolodrubetz. 2013. Mlc is a transcriptional activator with a key role in integrating CRP and IHF regulation of leukotoxin RNA synthesis in A. actinomycetemcomitans; J. Bacteriol. 195:2284-2297. PMID: 23475968