Ability of Wild-Type and Mutant Lysyl-tRNA Synthetase To Facilitate tRNA Lys Incorporation into Human Immunodeficiency Virus Type 1

Abstract

ABSTRACT The major human tRNA Lys isoacceptors, tRNA1,2Lys and tRNA3Lys, are selectively packaged into human immunodeficiency virus type 1 (HIV-1) during assembly, where tRNA3Lys acts as a primer for reverse transcription. Lysyl-tRNA synthetase (LysRS) is also incorporated into HIV-1, independently of tRNA Lys , via its interaction with Gag, and it is a strong candidate for being the signal that specifically targets tRNA Lys for viral incorporation. Expression of exogenous wild-type LysRS in cells results in an approximately twofold increase in the viral packaging of both LysRS and tRNA Lys . Herein, we show that this increase in tRNA Lys incorporation into virions is dependent upon the ability of LysRS to bind to tRNA Lys but not upon its ability to aminoacylate the tRNA Lys . COS7 cells were cotransfected with plasmids coding for both HIV-1 and either wild-type or mutant human LysRS, all of which are incorporated into virions with similar efficiency. However, N-terminally truncated LysRS, which binds poorly to tRNA Lys , does not increase tRNA Lys packaging into viruses, while C-terminally truncated LysRS, which binds to but does not aminoacylate tRNA Lys , still facilitates an increase in tRNA Lys packaging into virions.