Todd Rockway

Publications (4)12.56 Total impact

• Article: Mechanistic study of HCV polymerase inhibitors at individual steps of the polymerization reaction.

  Yaya Liu, Wen W Jiang, John Pratt, Todd Rockway, Kevin Harris, Sudthida Vasavanonda, Rakesh Tripathi, Ron Pithawalla, Warren M Kati
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  ABSTRACT: Little is known about the mechanism of HCV polymerase-catalyzed nucleotide incorporation and the individual steps employed by this enzyme during a catalytic cycle. In this paper, we applied various biochemical tools and examined the mechanism of polymerase catalysis. We found that formation of a productive RNA-enzyme complex is the slowest step followed by RNA dissociation and initiation of primer strand synthesis. Various groups have reported several classes of small molecule inhibitors of hepatitis C virus NS5B polymerase; however, the mechanism of inhibition for many of these inhibitors is not clear. We undertook a series of detailed mechanistic studies to characterize the mechanisms of inhibition for these HCV polymerase inhibitors. We found that the diketoacid derivatives competitively bind to the elongation NTP pocket in the active site and inhibit both the initiation and elongation steps of polymerization. While both benzimidazoles and benzothiadiazines are noncompetitive with respect to the active site elongation NTP pocket, benzothiadiazine compounds competitively bind to the initiation pocket in the active site and inhibit only the initiation step of de novo RNA polymerization. The benzimidazoles bind to the thumb allosteric pocket and inhibit the conformational changes during RNA synthesis. We also observed a cross interaction between the thumb allosteric pocket and the initiation pocket using inhibitor-inhibitor cross competition studies. This information will be very important in designing combination therapies using two small molecule drugs to treat hepatitis C virus.
  Biochemistry 10/2006; 45(38):11312-23. · 3.42 Impact Factor
• Article: Mutations conferring resistance to a hepatitis C virus (HCV) RNA-dependent RNA polymerase inhibitor alone or in combination with an HCV serine protease inhibitor in vitro.

  Hongmei Mo, Liangjun Lu, Tami Pilot-Matias, Ron Pithawalla, Rubina Mondal, Sherie Masse, Tatyana Dekhtyar, Teresa Ng, Gennadiy Koev, Vincent Stoll, Kent D Stewart, John Pratt, Pam Donner, Todd Rockway, Clarence Maring, Akhteruzzaman Molla
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  ABSTRACT: Compounds A-782759 (an N-1-aza-4-hydroxyquinolone benzothiadiazine) and BILN-2061 are specific anti-hepatitis C virus (HCV) agents that inhibit the RNA-dependent RNA polymerase and the NS3 serine protease, respectively. Both compounds display potent activity against HCV replicons in tissue culture. In order to characterize the development of resistance to these anti-HCV agents, HCV subgenomic 1b-N replicon cells were cultured with A-782759 alone or in combination with BILN-2061 at concentrations 10 times above their corresponding 50% inhibitory concentrations in the presence of neomycin. Single substitutions in the NS5B polymerase gene (H95Q, N411S, M414L, M414T, or Y448H) resulted in substantial decreases in susceptibility to A-782759. Similarly, replicons containing mutations in the NS5B polymerase gene (M414L or M414T), together with single mutations in the NS3 protease gene (A156V or D168V), conferred high levels of resistance to both A-782759 and BILN-2061. However, the A-782759-resistant mutants remained susceptible to nucleoside and two other classes of nonnucleoside NS5B polymerase inhibitors, as well as interferon. In addition, we found that the frequency of replicons resistant to both compounds was significantly lower than the frequency of resistance to the single compound. Furthermore, the dually resistant mutants displayed significantly reduced replication capacities compared to the wild-type replicon. These findings provide strategic guidance for the future treatment of HCV infection.
  Antimicrobial Agents and Chemotherapy 11/2005; 49(10):4305-14. · 4.84 Impact Factor
• Article: Inhibition of human immunodeficiency virus type I integrase by naphthamidines and 2-aminobenzimidazoles.

  Tim Middleton, Hock B Lim, Debra Montgomery, Todd Rockway, Hua Tang, Xueheng Cheng, Liangjun Lu, Hongmei Mo, William E Kohlbrenner, Akhteruzzaman Molla, Warren M Kati
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  ABSTRACT: Retroviral integrases catalyze two of the steps of insertion of proviral DNA into the host genomic DNA. Inhibitors that target the second step, strand transfer into the host DNA, have been demonstrated to have antiviral activity in cell culture. We describe two classes of HIV-1 integrase inhibitors that block strand transfer, one based on a naphthamidine core and one on a benzimidazole core. While the naphthamidine compounds showed some propensity to interact with the DNA substrate, both classes were shown to bind directly to integrase. The naphthamidine compounds showed activity in cell culture, and a direct effect on integrase was indicated by an increase in 2-LTR products in the presence of a naphthamidine compound. These two classes of compounds represent potential starting points for the development of new classes of integrase inhibitors.
  Antiviral Research 11/2004; 64(1):35-45. · 4.30 Impact Factor
• Chapter: Antiviral Agents, DNA

  Tim Middleton, Todd Rockway
  01/2003; , ISBN: 9780471266945