Faculty

Michael A. Parniak, Ph.D. Professor, Department of Microbiology and Molecular Genetics - School of Medicine, and Department of Infectious Diseases and Microbiology - Graduate School of Public Health (Secondary Appointments) Director, Molecular Virology and Microbiology Graduate Program, Interdisciplinary Biomedical Graduate Program - School of Medicine E-mail: parniak@mgb.pitt.edu Phone: 412-648-1927 Fax: 412-648-8521 Address: W1142 BST 200 Lothrop Street Pittsburgh, PA 15261

Education

PhD (Chemistry); University of Waterloo, Waterloo ON, Canada; 1978

Research Interests

Mechanisms of action and resistance to HIV-1 to reverse transcriptase inhibitors; RNase H as a potential antiviral, antifungal, and antibacterial target; nonnucleoside reverse transcriptase inhibitors as anti-HIV-1 microbicides; and structural and biological properties of modified arabino antisense oligonucleotides.

Research Summary

Research in our laboratory uses a multidisciplinary approach involving biochemistry, biophysics, chemistry, molecular biology and molecular virology in a variety of projects related to HIV/AIDS:

• Studies of HIV reverse transcriptase (RT) structure and function. These include the role of RT subunit interactions in the expression of enzyme activity, molecular events in the proteolytic processing of RT during HIV maturation, and identification and development of inhibitors of RT subunit interactions.
• Mechanisms of antiviral inhibitor action and resistance. These include mechanistic analyses of the phenotypes arising from different mutations associated with resistance to nucleoside RT inhibitors, especially mutations associated with multidrug resistance, and the role of multiple mutations in resistance to tight-binding nonnucleoside RT inhibitors.
• Development of new antiviral agents against novel HIV targets. Our primary focus is on the identification and characterization of “drug-like” compounds that inhibit HIV RT-associated ribonuclease H activity.
• Evaluation of nonucleoside RT inhibitors for use in topical microbicide formulations to prevent sexual transmission of HIV. In addition to these HIV-related research projects, the laboratory is also involved in the development of new antisense oligonucleotide technologies. These studies focus on the role of nucleotide sugar conformation and flexibility in antisense action, especially in the ability of antisense to elicit ribonuclease H degradation of target mRNA.

Techniques: Site-specific mutagenesis, transient (pre-steady state) kinetic analysis of enzyme function, biochemical probes of protein structure and function, molecular modeling of drug-receptor interactions, cell and virus culture, antiviral drug susceptibility assays, development and characterization of HIV resistance to novel antiviral agents.

Selected Publications

• Hossain MM, Parniak MA. In vitro microbicide activity of the nonnucleoside reverse transcriptase inhibitor (NNRTI) UC781 against NNRTI-resistant human immunodeficiency virus type 1. J Virol 2006; 80, 4440-4446.

• Gupta P, Ratner D, Patterson BK, Caruso L, Rohan LC, Parniak MA , Isaac CE, Hillier S. Use of frozen-thawed cervical tissues in the organ culture system to measure anti-HIV activities of candidate microbicides. AIDS Res Hum Retroviruses 2006; 22, 419-424.

• Sluis-Cremer N, Arion D, Parikh U, Koontz D, Schinazi R, Mellors JW, Parniak MA . The 3’-azido group is not the primary determinant of AZT responsible for the excision phenotype of AZT-resistant HIV-1. J Biol Chem 2005; 280, 29047-29052.

• Abram ME, Parniak MA . Virion instability of human immunodeficiency virus type 1 reverse transcriptase (RT) mutated in the protease cleavage site between RT p51 and the RT ribonuclease H domain. J Virol 2005; 79, 11952-11961.

• Budihas SR, Gorshkova I, Gaidamakov S, Wamiru A, Bona MK, Parniak MA , Crouch RJ, McMahon JB, Beutler JA, Le Grice SFJ. Selective inhibition of HIV-1 reverse transcriptase-associated ribonuclease H activity by hydroxylated tropolones. Nucl Acids Res 2005; 33, 1249-1256.

• Shaw-Reid CA, Feuston B, Munshi V, Getty K, Krueger J, Hazuda DJ, Parniak MA, Miller MD, Lewis D. Dissecting the effects of DNA polymerase and ribonuclease H inhibitor combinations on HIV-1 reverse transcriptase activities. Biochemistry 2005; 44, 1595-1606.

• Chan KC, Budihas SR, Le Grice SFJ, Parniak MA, Crouch RJ, Gaidamakov SA, Isaaq HJ, Wamiru A, McMahon JB, Beutler JA. A capillary electrophoretic assay for RNase H enzymatic activity. Anal Biochem 2004; 331:296-302.

• Sluis-Cremer N, Arion D, Abram ME, Parniak MA. Proteolytic processing of an HIV-1 gag-pol polyprotein precursor: Insights into the mechanism of reverse transcriptase p66/p51 heterodimer formation. Int J Biochem Cell Biol 2004; 36: 1836-1847.

• Parniak MA (editor), “Molecular Biology of HIV”, Special Issue of Int J Biochem Cell Biol 2004; 36: 1665-1859.

• Parniak MA , Min KL, Budihas SR, Le Grice SFJ, Beutler JA. A fluorescence-based high throughput screening assay for inhibitors of HIV reverse transcriptase associated ribonuclease H activity. Anal Biochem 2003; 322: 33-39.

• Sluis-Cremer N, Arion D, Abram ME, Parniak MA. Proteolytic processing of an HIV-1 gag-pol polyprotein precursor: Insights into the mechanism of reverse transcriptase p66/p51 heterodimer formation. Int J Biochem Cell Biol 2004; 36: 1836-1847

• Mangos MM, Min KL, Viazkovina E, Galarneau A, Parniak MA, Damha MJ. Efficient RNase H-directed cleavage of RNA using DNA or 2’F-ANA constructs containing acyclic nucleotide inserts. J Am Chem Soc 2003; 125:654-661

• Damha MJ, Min KL, Viazkovina E, Galarneau A, Parniak MA Oligonucleotides comprised of alternating 2’-deoxy-2’-fluoro- b -D-arabinonucleosides and D-2’-deoxyribonucleosides (FANA-DNA “altimers”) induce efficient RNA cleavage mediated by RNase H. Biorg. Med. Chem Lett. 2002; 12:2651-2654.

• Sluis-Cremer N, Arion D, Parniak MA. Destabilization of the HIV-1 reverse transcriptase dimer upon interaction with N-acyl hydrazone inhibitors. Mol Pharmacol 2002; 61:398-405.

• Rigourd M, Ehresmann C, Parniak MA, Ehresmann B, Marquet R. AZT-resistant reverse transcriptase is not resistant during the initiation of HIV-1 reverse transcription. J Biol Chem 2002; 277:18611-18618.

• Borkow G, Salomon H, Wainberg MA, Parniak MA. Attenuated infectivity of human immunodeficiency virus type 1 produced from epithelial cells pretreated with the nonnucleoside reverse transcriptase inhibitor UC781. AIDS Res. Hum. Retrovir. 2002; 18:711-714

• Motakis D, Parniak MA. A tight-binding mode of inhibition is essential for the anti-HIV-1 microbicidal activity of nonnucleoside reverse transcriptase inhibitors. Antimicrob. Agents Chemother. 2002; 46:1851-1856.

• Lok CN, Damha MJ, Viazovkina E, Min KL, Nagy E, Wilds CL, Parniak MA. Potent gene-specific inhibitory properties of mixed-backbone antisense oligonucleotides comprised of 2’-deoxy-2’-fluoro-D-arabinose and 2’ deoxyribose nucleotides. Biochemistry 2002; 41: 3457-3467.

• Arion D, Sluis-Cremer N, Abram ME, Min KL, Fletcher RS, Parniak MA. Mutational analysis of Y501 of HIV-1 reverse transcriptase: Effects on ribonuclease H activity and inhibition of this activity by N-acyl hydrazones. J Biol Chem 2002; 277:1370-1374.