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Title: Viral precursor protein P3 and its processed products perform discrete and essential functions in the poliovirus RNA replication complex

Author
item Spear, Allyn
item OGRAM, SUSHMA A - University Of Florida
item MORASCO, B. JOAN - University Of Florida
item SMERAGE, LUCIA - University Of Florida
item FLANEGAN, JAMES - University Of Florida

Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2015
Publication Date: 8/21/2015
Citation: Spear, A., Ogram, S., Morasco, B., Smerage, L.E., Flanegan, J.B. 2015. Viral precursor protein P3 and its processed products perform discrete and essential functions in the poliovirus RNA replication complex. Virology. 485:492-501. doi: http://dx.doi.org/10.1016/j.virol.2015.07.018.

Interpretive Summary: Even with current vaccines, poliovirus is still a problem in developing countries. Knowing the details of how the virus works can help in designing new drugs for both poliovirus and other related viruses. Using a test-tube virus replication system, we looked at different parts of how the virus starts replicating and we were able to show that multiple copies of the same protein, P3, were doing separate and different actions. This means that this P3 protein must be binding to other copies or to the virus genome in multiple ways. These new interactions are possible places that can be studied to find drugs to treat or prevent infection from poliovirus or related viruses.

Technical Abstract: The differential use of protein precursors and their products is a key strategy used during poliovirus replication. To characterize the role of protein precursors during replication, we examined the complementation profiles of mutants that inhibited 3D polymerase or 3C-RNA binding activity. We showed that 3D entered the replication complex in the form of its precursor, P3 (or 3CD), and was cleaved to release active 3D polymerase. Furthermore, our results showed that P3 is the preferred precursor that binds to the 5'CL. Using reciprocal complementation assays, we showed that one molecule of P3 binds the 5'CL and that a second molecule of P3 provides 3D. In addition, we showed that a second molecule of P3 served as the VPg provider. These results support a model in which P3 binds to the 5'CL and recruits additional molecules of P3, which are cleaved to release either 3D or VPg to initiate RNA replication.