BPS2026 – Architecture of HIV-1 capsid bound to the dynein transport machinery

HIV-1’s retrograde transport toward the nucleus is mediated by the microtubule motor protein dynein. Recently, we successfully reconstituted dynein-driven HIV-1 trafficking along microtubules in vitro. Our findings revealed that the HIV-1 core directly interacts with dynein and independently recruits an adaptor protein for activation, allowing the virus to engage multiple dynein cargo adaptors for movement. Building on these discoveries, we sought to define the specificity of the interaction between dynein and HIV-1. Using biochemical and single-molecule assays, we demonstrated that in vitro-assembled HIV-1 capsids can be directly recruited to microtubules and transported by dynein. On the dynein side, we identified the tail domain as the primary region that engages with HIV-1, with evidence indicating that the LC8 light chain may play a crucial role in this interaction. To further pinpoint dynein's binding site on the HIV-1 capsid, we utilized cryo-electron tomography (cryo-ET) on an in vitro complex of dynein, HIV-1 capsids, and microtubules. Unexpectedly, we observed that dynein predominantly interacts with the ends of HIV-1 capsid assemblies, with a strong preference for binding at the open end of HIV-1 tubes. These findings suggest that dynein binding may be mediated through the internal lumen of the assembled HIV-1 capsid rather than its outer surface. To test this, we imaged long HIV-1 capsid tubes to determine whether end-on attachment is utilized during trafficking in vitro. Interestingly, our results revealed that the majority of motile events involving capsid assemblies are driven by end-on attachment, as observed through fluorescence (TIRF) and label-free (IR) microscopy. Our findings suggest that a specific capsid lumen structure is recognized by dynein for HIV-1 trafficking along microtubules.