Dr. Lawrence Kleiman received his Ph.D. from the Johns Hopkins University in 1970. Subsequently, he did post-doctoral training at both the Johns Hopkins University and the Beatson Institute for Cancer Research in Scotland. In 1975, Dr. Kleiman started his career as a Staff Investigator at the Lady Davis Institute for Medical Research, Jewish General Hospital in Montreal. In 1992 Dr. Kleiman became a professor in the Departments of Medicine and Microbiology and Immunology of McGill University, and began his long term studies on aspects of HIV-1 assembly that promote the function of tRNALys3 as the primer for reverse transcription in HIV-1. He currently has generous funding from both the Canadian Institute of Health Research (CIHR) and National Institutes of Health (NIH) to support this work. Dr. Kleiman has trained many post-doctoral fellows and graduate students and has published over 100 peer-reviewed papers and review articles. His laboratory generally employs nine to ten people, primarily post-doctoral fellows and research associates, with whom he has daily, informal contact.
Major Research Activities
Aspects of HIV assembly that promote the annealing of primer tRNALys3 to HIV-1 genomic RNA. Upon HIV-1 infection of the target cell, the genomic RNA of HIV-1 is converted into a double-stranded DNA by the enzyme reverse transcriptase, and this DNA is then inserted into the cell’s DNA, where it codes for new viral proteins. The initiation of reverse transcription is primed by a cellular tRNA, tRNALys3, which is annealed to viral RNA sequences near the 5´ terminus of the viral RNA. The annealing of tRNALys3 to HIV-1 genomic RNA, which occurs during HIV-1 assembly, is absolutely essential for the production of new viruses. The goals of Dr. Kleiman's research are: 1) to clarify the molecular processes involved in the annealing of tRNALys3 to the primer binding site (PBS) in viral RNA; and 2) to develop assays amenable for high throughput screening of small compound libraries for detecting inhibitors of these processes.
Most tRNALys3 in the cell is found bound to lysyl-tRNA synthetase (LysRS), the protein that aminoacylates the tRNA with lysine. During assembly of the virus at the cell membrane, a Gag/GagPol/viral RNA complex interacts with the tRNALys3/LysRS complex, with Gag interacting specifically with LysRS, and the RT sequences in GagPol interacting with tRNALys3. This forms the tRNALys3 annealing complex. It is this specific interaction between Gag and LysRS that targets tRNALys3 for concentration at the site of viral assembly. An assay for the Gag/LysRS interaction, using fluorescence anisotropy, has been developed, and is now being used for high throughput screening of compound libraries to search for inhibitors of this interaction. His team is also studying how the arrangement of components within the tRNALys3 annealing complex facilitate transfer of tRNALys3 from LysRS to RT, and from RT to the site of annealing in viral RNA, the primer binding site. In addition to viral proteins, these interactions involve host cell factors such as RNA helicase A.
Recent Publications
Li, X., Liang, C., and Kleiman, L. Coordinate roles of Gag and RNA helicase A in promoting the annealing of tRNALys3 to HIV-1 RNA. (2011) J. Virol. 85:1847-1860.
Kleiman L, Jones CP, Musier-Forsyth K. Formation of the tRNALys packaging complex in HIV-1. (2010) FEBS Lett. 584:359-65.
Guo, F., Saadatmand, J., Niu, M., and Kleiman, L. Roles of Gag and NCp7 in facilitating tRNALys3 annealing to viral RNA in HIV-1. (2009) J. Virol. 83: 8099-8107.