RNA Polymerases and RNA-binding Proteins in Viral Infection and Mitochondrial Disease
Since its inception, the primary goal of this laboratory has been development of strategies to treat or to prevent infections by RNA viruses. We have used poliovirus and hepatitis C virus (HCV) as our primary model systems. Our expertise in virology, biochemistry and mechanistic enzymology brings a unique combination of intellectual and technical resources to the study of RNA viruses. Our initial focus was the viral RNA-dependent RNA polymerase (RdRp). In particular, we were interested in the kinetic, thermodynamic and structural basis for fidelity of nucleotide incorporation, a topic of considerable importance not only for accurate maintenance, transmission and expression of genetically encoded information but also for targeting the RdRp for antiviral therapy. These studies have led to exciting discoveries that have moved the lab into many new areas, including enzyme dynamics, vesicular trafficking, innate immunity, vaccine development and mitochondrial molecular biology. Our work is highly collaborative and includes research teams from academia (local, national and international), government and industry. We currently have projects in the following areas: RNA-dependent RNA polymerase mechanism, Viral attenuation and vaccine development, Picornavirus genome replication, Biochemical mechanisms and biological functions of HCV NS3 and NS5a proteins, Mitochondrial transcription and disease, and Lethal mutagenesis as an antiviral strategy.
Model for formation of picornavirus genome replication and packaging complexes. In a normal cell, COPII-coated vesicles originate from the ER. These vesicles can be tethered to other COPII-coated vesicles and eventually fuse. In a picornavirus-infected cell, viral protein 2BC hijacks the COPII-coated vesicles and these 2BC-COPII-coated vesicles become eRCs that serve for early replication. As the concentration of viral protein 3CD increases, eRCs are transformed to lRCs which ultimately give rise to packaging complexes.
Hypothetical model for human mitochondrial transcription cycle. (a) Formation of the pre-initiation complex may occur with factors and polymerase interacting once bound to DNA (pathway I), prior to associating with DNA (pathway II) or some combination. (b) Control region for mitochondrial transcription: +1 with (numbers), transcription start sites in mtDNA; shaded rectangles, putative mtTFA-binding sites (TFA BS); circles, IPR sites similar to canonical TFA BS. (c) The pre-initiation complex on LSP is stable and requires both h-mtTFA and h-mtTFB2, unlike that on HSP1. Formation of the open complex represents the primary rate-limiting step on linear templates. Promoter-specific, post-initiation events limit formation of the elongation complex. These events are promoter specific. This post-initiation control could reflect remodeling of factor-factor, factor-polymerase and/or polymerase-RNA/DNA interactions. Elongating polymerase likely functions without factors, as factors and template can act catalytically.