Characterization of HIV‐1 Unmyrostolated Gag Polyprotein Interactions with the MAL HIV‐1 Genome

Abstract

Human Immunodeficiency Virus (HIV‐1) is a retrovirus that targets CD4 T‐cells within the immune system which leads to compromising the immune system and effectively resulting in the development of Acquired Immune Deficiency Syndrome, AIDS. Current antiretroviral gene therapies target areas of the HIV‐1 replication cycle that are susceptible to mutations, resulting in reduced efficiency of these treatments. Also, the cocktail of drugs that are typically prescribed to patients can result in adverse effects such as drug toxicity after long‐term use. There is a need for a new drug target that targets a highly conserved region of the viral replication cycle to allow for more effectivity in treatment. One region of the replication cycle known to be highly conserved is genomic recognition where the viral genome is recognized and bound by the viral Gag polyprotein. This highly conserved step stems from the minimal packaging region of the genome termed the Core Encapsidation Signal (CES) which is a portion of the viral genome located in the 5′‐Leader (5′‐L). It is proposed that the CES selectively recognizes and promotes the formation of Gag hexamers which become form the viral particle core. This research aims to understand the interactions of the CES and Gag polyprotein through the use of electrophoretic mobility shift assays (EMSAs) as well as isothermal titration calorimetry (ITC). These experiments allow for the identification of binding sites that may be occurring between the viral genome and the Gag proteins. Initial ITC data has shown CES to have seven binding sites however, this was only done with the Nucleocapsid (NC) domain of the Gag polyprotein, which is only a small domain of the Gag that only plays a role in RNA binding. Whereas the other structural domains play a role in packaging, assembly, and Using the full viral protein allows for a more biologically relevant evaluation for understanding the viral packaging cycle. In addition to EMSAs and ITC experiments, the future goal is to obtain a structure of the nucleation complex through the use of x‐ray crystallography and cryogenic electron microscopy. By understanding the protein‐RNA interaction that occurs during the formation of the nucleation complex of the virus and eventually elucidating the structure of this complex, antiretroviral therapies can begin to target this highly conserved region of the replication cycle.Support or Funding InformationThis research was funded by NIH/NIGMS grants RO1OM042561, 8RO1AI50498 and NIH/NIGMS MARC U*STAR T34 HHS 00026 National Research Service Award to UMBC. This research was supported in part by a grant to UMBC from the Howard Hughes Medical Institute through the HHMI Adaptation Project. We would like to thank the MARC U*STAR program and UMBC Summer Biomedical Training Program for the strong support.