Timothy Palzkill, Ph.D.
Professor and Chair
Department of Pharmacology
Cullen Trust for Higher Education Academic Chair
Education and Awards
- B.S., 1983, Biology, Creigton University
- Ph.D., 1988, Genetics, University of Iowa
- Postdoctoral Training, 1988-1990, Genentech Inc.
- Postdoctoral Training, 1990-1991, Stanford University
- MERIT Award from the National Institutes of Allergy and Infectious Diseases, National Institutes of Health, 2001
- Fellow of the American Academy of Microbiology
Analysis of the Determinants of Antibiotic Resistance Enzyme Stability and Substrate Specificity
A long term interest of my laboratory is the use of genetic and biochemical approaches to study protein structure and function with a focus on antibiotic resistance enzymes. These projects are focused on how mutations can alter the substrate specificity and thus the evolution of ß-lactamase enzymes. ß-lactamases provide antibiotic resistance by catalyzing the hydrolysis of the penicillins and cephalosporins to inactive products. Because of the strong selective pressure of antibiotic therapy, ß-lactamases evolve rapidly by acquiring amino acid substitutions that allow the enzymes to degrade newly developed penicillins and cephalosporins. We are using in vitro mutagenesis to randomize the coding sequences of ß-lactamases in the region of the active site to determine the range of amino acid types that are required for efficient hydrolysis of several different ß-lactam antibiotics. These studies provide basic information on the determinants of substrate specificity for an enzyme and practical information for the design of new antimicrobials that are less susceptible to the rapid evolution of resistance.
This research program is also aimed at understanding and engineering the binding specificity of a ß-lactamase inhibitor protein. This protein, named BLIP, is a natural product of the actinomycete, Streptomyces clavuligerus. BLIP interacts with several different class A ß-lactamases with varying affinities and is therefore a good model protein with which to study specificity determinants of protein-protein interactions. Site-directed mutagenesis has been used to identify the binding epitopes on BLIP important for interactions with several class A ß-lactamases. The results indicate that the sequence requirements for binding are similar for several enzymes with most of the binding free energy provided by two patches (hotspots) of aromatic residues on the surface of BLIP. In addition, the specificity of binding is significantly altered by mutation of charged residues on the surface of BLIP. This information has been used to design BLIP variants with broad or narrow specificity towards ß-lactamases.
In addition, my laboratory is involved in the development of small molecule inhibitors of metallo-ß-lactamases. These enzymes are a threat to antibiotic therapy because of their ability to efficiently hydrolyze virtually all ß-lactam antibiotics. The spread of genes encoding metallo-ß-lactamases among gram negative bacteria in recent years is a cause for concern and therefore the development of inhibitors of these enzymes is important. The overall objective of this research is to design and synthesize novel small molecule compounds that serve as broad-spectrum inhibitors of metallo-β-lactamases. This is being accomplished using a combination of rational drug design, synthetic chemistry, biological activity testing and x-ray crystallography. The ultimate goal of the research is to develop these inhibitors to be clinically useful drugs that can restore the antibacterial activity of β-lactam antibiotics (e.g., imipenem) against many highly drug resistant bacterial strains.
Development of Diagnostics and Therapeutics for Norovirus Infections
A collaborative project is being performed to develop diagnostics and therapeutics for norovirus infections. Noroviruses are a common cause of acute gastroenteritis. My laboratory serves as the protein purification and interaction core for the project and is also involved in the development of norovirus binding reagents and the discovery of inhibitors for an essential norovirus protease. Phage display has been used to identify peptides and single chain antibodies that bind norovirus capsid protein and are therefore potential detection reagents. The binding characteristics of these reagents are under study using a number of methods including surface plasmon resonance and calorimetry and tight binding peptides and antibodies are being evaluated for binding norovirus from clinical samples.
- Zhang, Z. and Palzkill, T. (2004). Dissecting the protein-protein interface between b-lactamase inhibitory protein and class A b-lactamases. J. Biol. Chem. 279: 42860-42866.
- Materon, I.C., Beharry, Z., Huang, W., Perez, C. and Palzkill, T. (2004). Analysis of the context dependent sequence requirements of active site residues in the metallo-b-lactamase IMP-1. J. Mol. Biol. 344: 653-663.
- Beharry, Z., and Palzkill, T. (2005). Functional analysis of active site residues of the fosfomycin resistance enzyme FosA from Pseudomonas aeruginosa. J. Biol. Chem. 280: 17786-17791.
- McKevitt, M., Brinkman, M.B., McLoughlin, M., Perez, C., Howell, J.K., Weinstock, G.M., Norris, S.J. and Palzkill, T. (2005). Genome scale identification of Treponema pallidum antigens. Infect. Immun. 73: 4445-4450.
- Brinkman, M.B., McKevitt, M., McLoughlin, M., Perez, P., Howell, J., Weinstock, G.M., Norris, S.J. and Palzkill, T. (2006). Reactivity of antibodies from syphilis patients to a protein array representing the Treponema pallidum proteome. J. Clin. Microb. 44: 888-891.
- Zwiefka, A., Palzkill, T., Han, R., Lukomska, E., Wojciechowski, J., Lukomski, S. (2006). Combinatorial search for ligands that specifically recognize the streptococcal collagen-like proteins Scl1 and Scl2. Int. Cong. Ser. 1289:207-210.
- Cushman, I., Palzkill, T. and Moore, M.S. (2006). Using peptide arrays to define nuclear carrier binding sites on nucleoporins. Methods 39: 329-341.
- Holloway, A.K., Palzkill, T. and Bull, J.J. (2007). Experimental evolution of gene duplicates in a bacterial plasmid model. J. Mol. Evol., 64:215-222.
- Wang, J., Zhang, Z., Palzkill, T. and Chow, D.-C. (2007). Thermodynamic investigation of the role of contact residues of BLIP for binding to TEM-1 b-lactamase. J. Biol. Chem. 282:17676-17684.
- Marciano, D.C., Kartouti, O.Y. and Palzkill, T. (2007). A fitness cost associated with the antibiotic resistance enzyme SME-1 b-lactamase. Genetics 176: 2381-2392.
- Rajagopala, S.V., Titz, B., Goll, J., Parrish, J.R., Wohlbold, K., Matthew T. McKevitt, M.T., Palzkill, T., Finley Jr., M.H., and Uetz, P. (2007). Functional genomics of bacterial motility. Mol. Sys. Biol. 3:128.
- Hyser, J.M., Zeng, C.Q., Beharry, Z., Palzkill, T. and Estes, M.K. (2008). Epitope mapping and use of epitope-specific antisera to characterize the VP5 binding site in rotavirus SA11 NSP4. Virology, In press.
- Gao, H., Wang, X., Zang, Z.K., Palzkill, T. and Zhou, J. (2008). Probing the regulon of ArcA in Shewanella oneidensis by integrated genomic analysis. BMC Genomics, In press.
- Brinkman, M.B., McGill, M.A., Petterson, J., Rogers, A., Matejkova, P., Smajs, D., Weinstock, G.M., Norris, S.J., and Palzkill, T. (2008). A novel Treponema pallidum antigen, TP0136, is an outer membrane protein that binds human fibronectin. Infect. Immun., In press.