The picornaviruses are a family of small positive sense single stranded RNA viruses that cause a wide range of diseases at an annual cost well into the hundreds of million dollars. Members include acute hepatitis A virus, the heart disease causing coxsackie B3 virus, rhinoviruses that cause more than half the occurrences of the common cold, and the paralyzing poliovirus. These viruses share a life cycle where RNA replication and viral assembly occurs in large membrane anchored replication complexes assembled on the surfaces of vesicles derived from the endoplasmic reticulum. The replication process is driven by a virally encoded RNA dependent RNA polymerase (3Dpol) that is responsible for the synthesis of all viral RNA. This research project is focused on the structure and assembly of the viral replication centers and on structure-function studies of the viral polymerases to understand mechanisms that control of elongation rates and replication fidelity. We have solved multiple crystal structures of 3Dpol as elongation complexes with bound RNA and these structures revealed a novel mechanism by which RdRPs close their active sites for catalysis in response to nucleotide binding. In this upcoming project period we will use biophysical and structural biology methods to further our mechanistic understanding of RNA translocation by 3Dpol and to solve the structures of viral initiation and uridylylation complexes. We will also use single molecule microscopy and particle tracking methods to directly visualize the in vitro assembly of viral replication complexes onto supported lipid bilayers.
The picornaviruses are a large family of viruses that cause a range of human diseases, including paralysis, hand foot and mouth disease in young children, and many cases of the common cold. These viruses replicate using a RNA-dependent RNA polymerase enzyme that is very error prone, resulting in viruses that can rapidly adapt to different cell types or become resistant to antiviral drugs. The primary focus of this project is to gain a structural understanding of the basic protein-protein and protein-RNA interactions that control the replication of these viruses. A secondary focus to understand why the viral polymerase is so error prone and use this information to interfere with its normal function in ways that could lead to new vaccines or antiviral drugs.
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