HIV-1 Nef stabilizes AP-1 on membranes without inducing ARF1-independent de novo attachment.
HIV-1 Nef affects the trafficking of numerous cellular proteins to optimize viral replication and evade host defenses. The adaptor protein (AP) complexes, which form part of the cytoplasmic coat of endosomal vesicles, are key cellular co-factors for Nef. Nef binds these complexes and alters their physiologic cycle of attachment and release from membranes. Specifically, while AP-1 normally becomes cytosolic when attachment events are blocked by inhibition of the GTPase cycle of ADP-ribosylation factor-1 (ARF1), the complex remains membrane-associated in Nef-expressing cells. To investigate the mechanism of this effect, we used a permeabilized cell system to detect the de novo attachment of exogenous AP-1 to endosomal membranes. Nef did not mediate de novo attachment independently of ARF1, despite its ability to maintain the association of AP-1 with endosomal membranes when the activity of ARF1 was blocked. We conclude that Nef stabilizes AP complexes on endosomal membranes after ARF1-dependent attachment. This stabilization may facilitate coat formation and stimulate the trafficking of multiple cellular proteins.
Coleman
Scott H
SH
Department of Medicine, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0679, USA.
Hitchin
Douglas
D
Noviello
Colleen M
CM
Guatelli
John C
JC
D020823:ADP-Ribosylation Factor 1 / Q000037:antagonists & inhibitors / Q000502:physiology*; D033961:Adaptor Protein Complex 1 / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015693:Gene Products, nef / Q000502:physiology*; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D007425:Intracellular Membranes / Q000737:chemistry / Q000378:metabolism*; D018613:Microscopy, Confocal; D008954:Models, Biological; D011485:Protein Binding; D054311:nef Gene Products, Human Immunodeficiency Virus
D033961:Adaptor Protein Complex 1; D004791:Enzyme Inhibitors; D015693:Gene Products, nef; D054311:nef Gene Products, Human Immunodeficiency Virus; D020823:ADP-Ribosylation Factor 1