Kelly Watters, PhD

Research Title: Comparative Analysis of Rhinovirus 2A Protease Cleavage of the Nuclear Pore Complex

Research Summary: The Palmenberg laboratory studies picornaviruses and are currently focusing their research on picornaviral proteins that inhibit nucleocytoplasmic trafficking in cells during infection. Human Rhinoviruses (HRVs) of the Enterovirus genus in the Picornaviridae family encode a protease, 2A, to shut off host cell activity that can inhibit their replication. Anti-host activities attributed to 2A include cleavage of eIF4G-I and –II to inhibit cellular mRNA translation and cleavage of nuclear pore proteins (nucleoporins) to disrupt intracellular nucleocytoplasmic signaling. Protein sequence alignments of over 150 different HRVs reveal significant sequence diversity in the 2A protease of these viruses, suggesting that the substrate specificity and proteolytic activity of the HRV 2A proteases may differ. Under the support of the Virology Training Grant, trainee Kelly Watters showed that different HRV 2As differentially target and cleave proteins in nucleoporins in nuclear pore complexes. Kelly proposed that differential cleavage of nucleoporins by each unique 2A probably works to inhibit specific intracellular signaling pathways through the nuclear pores in a virus strain specific manner. Kelly developed a unique cellular system to compare which transport pathways different HRV 2As disrupt and their rates of inhibition. For this system, she created stable HeLa cell lines expressing fluorescent proteins fused to different nuclear localizations signals that she then infected with virus or transfected with cDNAs encoding different HRV 2A proteases and observed in real-time if and when the nuclear reporter protein accumulates in the cytoplasm. The avidity and specificity with which different HRV 2As cleave Nups and their ability to disrupt nuclear transport pathways could alter antiviral signaling and affect virus replication levels, ultimately triggering different disease phenotypes and host immune responses.