Poster abstracts
Poster number 37 submitted by Alice Duchon
Examination of human lysyl-tRNA synthetase/tRNAlys primer recruitment and packaging into HIV
Alice Duchon (Department of Chemistry and Biochemistry, Center for RNA Biology, and Center for Retroviral Research, The Ohio State University, Columbus, OH 43210), Nathan Titkemeier (Department of Chemistry and Biochemistry, Center for RNA Biology, and 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), Michael Freitas (Department of Molecular Virology Immunology and Medical Genetics, 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, Center for RNA Biology, and Center for Retroviral Research, The Ohio State University, Columbus, OH 43210)
Abstract:
The primer for reverse transcription in HIV-1, human tRNA Lys3, is selectively packaged into virions along with tRNA Lys1,2. Human lysyl-tRNA synthetase (LysRS) , the only cellular factor known to interact specifically with all three tRNA Lys isoacceptors, is also packaged into HIV-1. Selective packaging of tRNA Lys 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, 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 phosphorylation of LysRS on Ser/Thr occurs only after HIV-1 infection. 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. A recent study suggests that HIV-1 Matrix (MA), a viral protein that functions in assembly by targeting Gag to the plasma membrane, preferentially binds certain cellular tRNAs, including tRNALys, over viral RNA. Studies to determine the specificity of MA binding in vitro are also underway.
Keywords: HIV-1 , LysRS, Assembly