Mycobacterium tuberculosis is the bacterium responsible for the infection known as tuberculosis, and is responsible for ~ 2 million deaths/year worldwide. Treatment of infections caused by M. tuberculosis require multiple drugs and long-term therapy because of the persistent nature and the high degree of antibiotic resistance associated with this organism. Consequently, new therapeutic alternatives are needed to circumvent these problems. The overall goals of our studies is to better understand the mechanisms that contribute to the pathogenicity of mycobacteria, to identify and characterize novel drug targets, and to synthesize inhibitors with the potential to function as novel antibiotics. The work involved with this research encompasses the areas of molecular biology, protein expression and purification, various biochemical measurements, bioinorganic chemistry and synthetic organic chemistry.

Mycothiol Biosynthesis and Metal Ion Homeostasis

Two potential defense mechanisms our lab is interested in are mycothiol biosynthesis and metal ion homeostasis. Mycothiol (MSH) is the unique thiol used by mycobacteria to protect against oxidative damage, while metal ion homeostasis (more specifically iron levels) has been shown to greatly impact disease progression in tuberculosis infections. Consequently, MSH and metal ion homeostasis may be two mechanisms that enable mycobacterial survival, thus implicating the enzymes involved in MSH biosynthesis, and the enzymes that utilize metal ions (ie. Fe, Zn), as potential targets for drug development. We are using an interdisciplinary approach to explore these hypotheses. For example, a typical project in our laboratory may involve one or more of the following approaches: using the combination of site-directed mutagenesis and various biochemical assays to probe the chemical mechanism and molecular recognition properties of specific enzymes, and/or using the information gained from these biochemical studies to design and/or optimize enzyme inhibitors through synthetic organic chemistry.

Hernick, M.; Fierke, C.A. Mechanisms of metal-dependent hydrolases in metabolism. Comprehensive Natural Products Chemistry II. Elsevier science (In press)

Lipton, A.S.; Heck, R.W.; Hernick, M.; Fierke, C.A.; Ellis, P.D. Residue ionization in LpxC directly observed by 67Zn NMR spectroscopy. Journal of the American Chemical Society. 2008, 130, 12671-9.   [Abstract]

Hernick, M.; Fierke, C. A. A method to assay inhibitors of lipopolysaccharide synthesis. New Antibiotic Targets. Molecular Medicine Series, Humana Press. In press.   [Abstract]

Hernick, M.; Fierke C. A. Molecular recognition by Escherichia coli UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase is modulated by bound metal ions. Biochemistry. 2006, 45, 14573-14581.    [Abstract]

Hernick, M.; Fierke, C. A. Catalytic mechanism and molecular recognition of E. coli UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase probed by mutagenesis. Biochemistry. 2006, 45, 15240-15248.   [Abstract]

Hernick, M; Fierke, C.A. Zinc-hydrolases: The mechanisms of zinc-deacetylases, Archives of Biochemistry and Biophysics, 2005, 433, 71-84.   [Abstract]

Hernick, M.; Gennadios, H. A.; Whittington, D. A.; Rusche, K.M.; Christianson, D. W.; Fierke C.A. UDP-3-O-((R)-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase functions through a general acid-base catalyst pair mechanism. Journal of Biological Chemistry, 2005, 280, 16969-16978.   [Abstract]

Hernick, M.; Borch, R.F. Studies on the mechanisms of activation of indolequinone phosphoramidate prodrugs. J. Med. Chem. 2003, 46, 148-154.    [Abstract]

Hernick, M.; Flader, C.; Borch, R.F. Design, synthesis and biological evaluation of indolequinone phosphoramidate prodrugs targeted to DT-diaphorase. J. Med. Chem. 2002, 45, 3540-3548.   [Abstract]