Poster abstracts
Poster number 15 submitted by Alice Duchon
HIV-1 exploits dynamic multi-aminoacyl-tRNA synthetase complex to enhance viral reverse transcription and replication
Alice Duchon (Department of Chemistry and Biochemistry, Center for RNA Biology, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210), Nathan Titkemeier (Department of Chemistry and Biochemistry, Center for RNA Biology, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210), Corine St. Gelais (Center for RNA Biology, Center for Retrovirus Research, and Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210), Li Wu (Center for RNA Biology, Center for Retrovirus 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, Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210)
Abstract:
A hallmark of retroviruses such as human immunodeficiency virus type-1 (HIV-1) is reverse transcription of genomic RNA into DNA, a reaction that is primed by host cell tRNAs. HIV-1 recruits human tRNALys3 to serve as the reverse transcription primer, yet all three human tRNALys isoacceptors are selectively packaged into virions via an interaction between lysyl-tRNA synthetase (LysRS) and the HIV-1 Gag polyprotein. LysRS is normally sequestered in a multi-aminoacyl-tRNA synthetase complex (MSC) together with 8 other tRNA-synthetases and three cellular factors. Previous studies have shown that components of the MSC can be mobilized in response to certain cellular stimuli. How LysRS is redirected from the MSC to viral particles for packaging is unknown. Here, we show that upon HIV-1 infection, LysRS is released from the MSC and partially relocalized to the nucleus. Heat inactivation of HIV-1 blocks nuclear localization but AZT treatment does not, suggesting LysRS release from the MSC occurs prior to reverse transcription. Knockdown of LysRS reduced progeny virion infectivity, release from the MSC and nuclear localization, as did treatment with a MEK inhibitor known to prevent phosphorylation of LysRS on Ser207. A phosphomimetic mutant (LysRSS207D) localized to the nucleus and rescued infectivity, whereas a phosphoablative mutant (LysRSS207A) remained cytosolic and failed to rescue infectivity. The ability of phosphoablative and phosphomimetic LysRS mutants to package tRNALys3 is currently being assessed. Taken together, this work suggests that HIV-1 takes advantage of the dynamic nature of the MSC to redirect and co-opt host cellular factors and thereby enhance its own replication. As HIV-1 is less likely to develop resistance to drugs that target host factors, we anticipate that these findings will lead to development of new therapeutic approaches to treat HIV-positive individuals.
Keywords: HIV-1, Aminoacyl-tRNA synthetase