Talk Abstracts

Talk on Saturday 10:45-11:00am submitted by Alice Duchon

Relocalization of Human Lysyl-tRNA Synthetase following HIV-1 Infection: Implications for tRNA Primer Recruitment

Alice Duchon (Department of Chemistry and Biochemistry, Center for RNA Biology, Center for Retroviral Research, The Ohio State University, Columbus, OH 43210), Nathan Titkemeier (Department of Chemistry and Biochemistry, Center for RNA Biology, Center for Retroviral Research, The Ohio State University, Columbus, OH 43210), Corine St. Gelais (Center for RNA Biology, Center for Retroviral Research, and Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210), Li Wu (Center for RNA Biology, Center for Retroviral Research, and Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210), Karin Musier-Forsyth (Department of Chemistry and Biochemistry, 2Center for RNA Biology, 3Center for Retroviral Research, The Ohio State University, Columbus, OH 43210)

Abstract:
All retroviruses use specific host cell tRNAs to prime reverse transcription of their retroviral RNA genomes into DNA. The primer for reverse transcription in HIV-1, human tRNA^Lys, is selectively incorporated into virions during viral assembly. We previously reported that human lysyl-tRNA synthetase (LysRS) is specifically packaged into HIV-1 leading to the enrichment of tRNA^Lys in virions. Cytoplasmic LysRS is normally localized to a dynamic mammalian multisynthetase complex (MSC). In addition to their well-known physiological function in translation, many tRNA synthetases are mobilized from the MSC to function in a wide variety of non-translational pathways. While some aspects of tRNA primer packaging into HIV-1 particles are now understood, the mechanism by which the LysRS/tRNA complex is diverted from its normal function in translation and recruited into viral particles is unclear. Using immunofluorescence and confocal microscopy we find that LysRS localization is dramatically altered upon HIV-1 infection. In uninfected cells, the majority of LysRS is located in the MSC, as expected, whereas following HIV-1 infection, LysRS is phosphorylated, released from the MSC, and traffics to the nucleus. Treatment with reverse transcription inhibitors does not block nuclear localization, suggesting that early stages of infection trigger LysRS release from the MSC. In contrast, treatment with a MAP kinase inhibitor known to block phosphorylation of LysRS does prevent nuclear localization of LysRS in HIV-infected cells. The implications of nuclear localization of LysRS for HIV-1 infectivity are being investigated.

Keywords: HiV, tRNA, LysRS