Abstract
Human Immunodeficiency Virus (HIV) is a leading cause of death in many parts of the world. HIV-2, endemic to West Africa, has infected over 2 million people globally. A key difference between HIV-2 and the more widespread HIV-1 is the HIV-2 protein Vpx, which facilitates infection in non-dividing cells by targeting SAMHD1, a host innate immune protein, for proteasomal degradation. This research aims to identify specific amino acid residues in HIV-2 ROD9 Vpx that are essential for mediating SAMHD1 degradation by the proteosome. I hypothesize that amino acid residues located in the C-terminal region of Vpx play a critical role in its ability to mediate SAMHD1 degradation. To test this hypothesis, site-directed mutagenesis was used to alter HIV-2 ROD9 Vpx; these mutated constructs were then transfected along with SAMHD1 into 293T cells. Protein degradation was evaluated by Western blot and densitometric analysis. While wildtype HIV-2 ROD9 Vpx mediated moderate (approximately 32%) degradation of SAMHD1, I identified a mutant, R77K, which led to approximately 60% SAMHD1 degradation. I then hypothesized that this enhanced degradation compared to all other HIV-2 ROD9 Vpx mutants observed might result from increased nuclear localization of the Vpx protein, thereby improving access to nuclear SAMHD1. However, contrary to my hypothesis, confocal microscopy analysis revealed that the HIV-2 ROD9 Vpx R77K mutant did not show increased nuclear localization compared to the wild-type, with no statistically significant difference observed between the two. This suggests that the enhanced SAMHD1 degradation mediated by the R77K variant occurred via a localization-independent mechanism. Together with previous work in the field, these findings increase fundamental understanding of this key viral protein.
Advisor
Allison Land
Committee Member
David Sharlin
Committee Member
Cecilia Noecker
Date of Degree
2025
Language
english
Document Type
Thesis
Degree
Master of Science (MS)
Program of Study
Biology
Department
Biological Sciences
College
Science, Engineering and Technology
Recommended Citation
Oladimeji, T. R. (2025). Impact of HIV-2 ROD9 Vpx mutations on SAMHD1 degradation and Vpx nuclear trafficking [Master’s thesis, Minnesota State University, Mankato]. Cornerstone: A Collection of Scholarly and Creative Works for Minnesota State University, Mankato. https://cornerstone.lib.mnsu.edu/etds/1554/
Rights Statement
