Poster abstracts

Poster number 100 submitted by Alice Duchon

Examination of Human Lysyl-tRNA Synthetase/tRNALys Primer Recruitment and Packaging into HIV-1

Alice Duchon (Department Chemistry and Biochemistry, Center for RNA Biology, Center for Retroviral Research), Nathan Titkemeier (Department Chemistry and Biochemistry, Center for RNA Biology, Center for Retroviral Research), Corine St. Gelais (Center for RNA Biology, Center for Retroviral Research, Department of Veterinary Biosciences), Li Wu (Center for RNA Biology, Center for Retroviral Research, Department of Veterinary), Karin Musier-Forsyth (Department Chemistry and Biochemistry, Center for RNA Biology, Center for Retroviral Research)

Abstract:
The primer for reverse transcription in HIV-1, human tRNALys3, is selectively packaged into virions along with tRNALys1,2. Human lysyl-tRNA synthetase (LysRS) , the only cellular factor known to interact specifically with all three tRNALys isoacceptors, is also packaged into HIV-1. Selective packaging of tRNALys depends on the ability of the tRNA to bind to LysRS and the presence of both host cell factors is required for optimal viral infectivity. LysRS is part of a dynamic mammalian multisynthetase complex (MSC) and has been shown to be mobilized from the MSC and 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. Here, we show that the expression of LysRS is unaltered upon HIV-1 infection, suggesting that the LysRS species packaged is recruited from an existing pool of LysRS. Using immunofluorescence and confocal microscopy with both HEK293T and HuT/CCR5+ cells, we find that LysRS trafficking is altered upon HIV-1 infection with more LysRS localized to the nucleus. LysRS-Gag and LysRS-genomic RNA co-localization studies are currently underway. Our studies also indicate that HIV infection results in phosphorylation of LysRS on Ser/Thr. We hypothesize that LysRS phosphorylation results in release from the MSC and nuclear entry. Studies to understand the significance of these findings for HIV infectivity are in progress.

Keywords: HIV, LysRS, tRNA