Joseph P. Dillard, Ph.D. Associate Professor, Medical Microbiology and Immunology Room 6301 Microbial Sciences Building 1550 Linden Drive Madison, WI 53706-1521 (608) 265-2837 Fax: (608) 262-8418 jpdillard@wisc.edu

Research Interests

My laboratory is investigating the molecular mechanisms of disease caused by the bacterium Neisseria gonorrhoeae, and, in particular, the mechanisms involved in causing pelvic inflammatory disease and disseminated gonococcal infection. This research focuses on the characterization of the gonococcal genetic island, a 57 kb region of horizontally acquired DNA, present in 80% of gonococcal isolates. Among other things, the island encodes a type IV secretion system that acts in the secretion of chromosomal DNA into the surrounding milieu.  Mutations in the type IV secretion system genes result in loss of DNA secretion into the culture medium and to altered interactions with host cells.

A second focus of research in the lab is the production of toxic peptidoglycan fragments. Gonococci are known to release a monomeric fragment of peptidoglycan that acts as a toxin in human Fallopian tube infection. We call this molecule peptidoglycan-derived cytotoxin (PGCT), but it has variously been referred to as tracheal cytotoxin, G(Anh)MTetra, or anhydro monomer. Peptidoglycan fragments are generated as a necessary part of cell wall expansion and cell division, but most gram-negative bacteria recycle the fragments for use in the cell wall. We have investigated how the peptidoglycan fragments are generated and identified specific lytic transglycosylases that function to produce these toxic molecules. Mutants lacking these lytic transglycosylases are being used to understand the role of PGCT in infection.

Training

1987, B.S., Georgia Institute of Technology, Atlanta, GA
1994, Ph.D., University of Alabama at Birmingham, Birmingham, AL
1994-98, Postdoctoral Fellow, Northwestern University Medical School, Chicago, IL

Publications – NCBI PubMed search for "J.P. Dillard"

Cloud-Hansen, Karen. A., Kathleen T. Hackett, Daniel L. Garcia, and Joseph P. Dillard. 2008. Neisseria gonorrhoeae uses two lytic transglycosylases to produce cytotoxic peptidoglycan monomers. J. Bacteriol. In press. doi:10.1128/JB.00506-08.

Garcia, Daniel L., and Joseph P. Dillard. 2008. Mutations in ampG or ampD affect peptidoglycan fragment release from Neisseria gonorrhoeae. J. Bacteriol. 190: 3799-3807.

Salgado-Pabón, Wilmara, Samta Jain, Nicholas Turner, Chris van der Does, and Joseph P. Dillard. 2007. A novel relaxase homologue is involved in chromosomal DNA processing for type IV secretion in Neisseria gonorrhoeae. Mol. Microbiol. 66:930-947. Note Cover illustration, vol 66-4.

Kohler, Petra L., Holly L. Hamilton, Karen Cloud-Hansen and Joseph P. Dillard. 2007. AtlA functions as a peptidoglycan lytic transglycosylase in the Neisseria gonorrhoeae type IV secretion system. J. Bacteriol. 189:5421-5428.

Garcia, Daniel L., and Joseph P. Dillard. 2006. AmiC functions as an N-acetylmuramyl-L-alanine amidase necessary for cell separation and can promote autolysis in Neisseria gonorrhoeae. J. Bacteriol. 188:7211-7222. (Note: See associated journal cover photo, Vol 188, No. 21).

Hamilton, Holly L., and Joseph P. Dillard. 2006. Natural transformation of Neisseria gonorrhoeae: from DNA donation to homologous recombination. Mol Microbiol. 59:376-385.

Dillard, Joseph P., and Kathleen T. Hackett. 2005. Mutations affecting peptidoglycan acetylation in Neisseria gonorrhoeae and Neisseria meningitidis. Infect. Immun. 73: 5697-5705.

Kohler, Petra L., Karen A. Cloud, Kathleen T. Hackett, Eric T. Beck, and Joseph P. Dillard. 2005. Characterization of the role of LtgB, a putative lytic transglycosylase in Neisseria gonorrhoeae.  Microbiology. 151: 3081-3088.

Hamilton, Holly L., Nadia M. Dominguez, Kevin J. Schwartz, Kathleen T. Hackett, and Joseph P. Dillard. 2005. Neisseria gonorrhoeae secretes chromosomal DNA via a novel type IV secretion system. Mol Microbiol. 55:1704-1721.

Cloud, Karen A., and Joseph P. Dillard. 2004. Mutation of a single lytic transglycosylase causes aberrant septation and inhibits cell separation of Neisseria gonorrhoeae. J. Bacteriol. 186:7811-7814.

Cloud, Karen A. and Joseph P. Dillard. 2002. A lytic transglycosylase of Neisseria gonorrhoeae is involved in peptidoglycan-derived cytotoxin production. Infect. Immun. 70:2752-2757.

Hamilton, Holly L., Kevin J. Schwartz, and Joseph P. Dillard. 2001. Insertion-duplication mutagenesis of Neisseria: Use in characterization of DNA transfer genes in the gonococcal genetic island. J. Bacteriol. 183:4718-4726.

Dillard, Joseph P., and H. Steven Seifert. 2001. A variable genetic island specific for Neisseria gonorrhoeae is involved in providing DNA for genetic transformation and is found more often in disseminated infection isolates. Mol. Microbiol. 41:263-277.