HIV-1 Gag MA domain binds to cardiolipin in a binding mode distinct from virus assemble mediator PI(4,5)P₂

The human immunodeficiency virus type 1 (HIV-1) Gag protein is responsible for facilitating HIV-1 virion assembly and budding. Our study demonstrates that cardiolipin (CL), a component found in the inner mitochondrial membrane, exhibits the highest binding affinity to the N-terminal MA domain of the HIV-1 Gag protein within the lipid group of host cells. To assess this binding interaction, we synthesized short acyl chain derivatives of CL and employed surface plasmon resonance (SPR) analysis to determine the dissociation constants (Kd) for CL and the MA domain. Simultaneously, we examined the Kd of D-myo-phosphatidylinositol 4,5-bisphosphate (PI(4,5)P₂ ) derivatives, known to play a crucial role in virion formation. Among all the derivatives, Tetra-C₇ -CL exhibited the lowest Kd value (Kd = 30.8 ± 6.9 μM) for MA binding on the CL analog-immobilized sensorchip, indicating a higher affinity. Similarly, the Kd value of Di-C₇ -PIP2 (Kd = 36.6 ± 4.7 μM) was the lowest on the PI(4,5)P₂ analog-immobilized sensorchip. Thus, Tetra-C₇ -CL binds to the MA domain using a distinct binding mode while displaying a comparable binding affinity to Di-C₇ -PIP2. This discovery holds significant implications for comprehending the virological importance of CL-MA domain binding, such as its subcellular distribution, including mitochondrial translocation, and involvement in viral particle formation in concert with PI(4,5)P₂ . Furthermore, this study has the potential to contribute to the development of drugs in the future.