Intracellular transport of cargos, including many viruses, involves directed movement on microtubules mediated by motor proteins. While a number of viruses bind motors of opposing directionality, how they associate with and control these motors to accomplish directed movement remains poorly understood. Here we show that human immunodeficiency virus type 1 (HIV-1) associates with the kinesin-1 adaptor protein, Fasiculation and Elongation Factor zeta 1 (FEZ1). RNAi-mediated FEZ1 depletion blocks early infection, with virus particles exhibiting bidirectional motility but no net movement to the nucleus. Furthermore, both dynein and kinesin-1 motors are required for HIV-1 trafficking to the nucleus. Finally, the ability of exogenously expressed FEZ1 to promote early HIV-1 infection requires binding to kinesin-1. Our findings demonstrate that opposing motors both contribute to early HIV-1 movement and identify the kinesin-1 adaptor, FEZ1 as a capsid-associated host regulator of this process usurped by HIV-1 to accomplish net inward movement toward the nucleus.
Summary
Stable microtubule (MT) subsets form distinct networks from dynamic MTs and acquire distinguishing posttranslational modifications, notably detyrosination and acetylation. Acting as specialized tracks for vesicle and macromolecular transport, their formation is regulated by the end-binding protein, EB1, which recruits proteins that stabilize MTs. We show that HIV-1 induces the formation of acetylated and detyrosinated stable MTs early in infection. Although the MT depolymerizing agent nocodazole affected dynamic MTs, HIV-1 particles localized to nocodazole-resistant stable MTs and infection was minimally affected. EB1 depletion or expression of an EB1 carboxy-terminal fragment that acts as a dominant negative inhibitor of MT stabilization, prevented HIV-1-induced stable MT formation and suppressed early viral infection. Furthermore, we show that the HIV-1 matrix protein targets the EB1-binding protein, Kif4 to induce MT stabilization. Our findings illustrate how specialized MT-binding proteins mediate MT stabilization by HIV-1 and the importance of stable MT subsets in viral infection.
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