Poster abstracts

Poster number 29 submitted by Danni Jin

Non-canonical Function of Glutamyl-Prolyl-tRNA Synthetase (EPRS) in HIV-1 Infection

Danni Jin, Nathan Titkemeier, Alice Duchon (Department of Chemistry and Biochemistry, Center for RNA Biology, Center for Retrovirus Research, The Ohio State University, Columbus, OH, 43210), Yiping Zhu (Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University, New York, NY, 10032), Corine St. Gelais (Department of Veterinary Biosciences, Center for RNA Biology, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210), Li Wu (Department of Veterinary Biosciences, Center for RNA Biology, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210), Stephen P. Goff (Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University, New York, NY, 10032), Karin Musier-Forsyth (Department of Chemistry and Biochemistry, Center for RNA Biology, Center for Retrovirus Research, The Ohio State University, Columbus, OH, 43210)

Abstract:
Aminoacyl-tRNA synthetases (AARSs) are essential components of the cellular translational machinery responsible for charging tRNAs with their cognate amino acids. Many mammalian AARSs also participate in alternate functions outside of their canonical role in translation. The mammalian glutamyl-prolyl-tRNA synthetase (EPRS) was reported to exhibit potent antiviral activity against RNA viruses, including influenza A virus and vesicular stomatitis virus, by upregulating the innate immune responses (Lee et al., Nat. Immunol., 2016). The mammalian multi-aminoacyl-tRNA synthetase complex (MSC) contains three scaffold proteins and eight AARSs, including EPRS. Based on published studies, all MSC components were identified in the interactomes of HIV-1 Gag and matrix (MA) proteins, and siRNA knockdown of EPRS leads to increased HIV-1 replication in HIV-permissive HeLa cells (Jäger et al., Nature, 2012; Engeland et al., Virology, 2014), raising the possibility that EPRS is an anti-HIV-1 factor. However, the mechanism by which EPRS inhibits HIV-1 infection is unclear. EPRS is a bifunctional AARS with a linker domain between the two synthetase cores, and we hypothesize that the linker domain is important for mediating HIV-1 infection. Our data show that HIV-1 MA interacts with the MSC through the linker domain of EPRS in an RNA-dependent manner. However, the RNA specificity required for bridging the MA-EPRS interaction remains unknown. Furthermore, expression of the linker domain in HEK293T cells inhibits HIV-1 gene expression. We hypothesize that this virus-host interaction contributes to efficient viral infection. In accordance with this hypothesis, HIV-1 with MA mutations affecting the EPRS interaction are less infectious than wild-type viruses. Moreover, we observe decreased EPRS expression in HuT/CCR5 cells infected with single-cycle HIV-1, and in HEK293T cells that stably express HIV-1 MA. Therefore, we propose that HIV-1 has evolved a mechanism to counteract the anti-viral effect of EPRS through its interaction with MA.

References:
Lee E-Y, Lee H-C, Kim H-K, et al. Infection-specific phosphorylation of glutamyl-prolyl tRNA synthetase induces antiviral immunity. Nat Immunol. 2016;(September). doi:10.1038/ni.3542.
Jäger S, Cimermancic P, Gulbahce N, et al. Global landscape of HIV-human protein complexes. Nature. 2012;481(7381):365-370. doi:10.1038/nature10719.
Engeland CE, Brown NP, Börner K, et al. Proteome analysis of the HIV-1 Gag interactome. Virology. 2014;460-461:194-206. doi:10.1016/j.virol.2014.04.038.

Keywords: HIV-1, Aminoacyl-tRNA synthetase, EPRS