title: Human ESCRT-II complex and its role in human immunodeficiency virus type 1 release.
abstract: The budding of many enveloped RNA viruses, including human immunodeficiency virus type 1 (HIV-1), requires some of the same cellular machinery as vesicle formation at the multivesicular body (MVB). In Saccharomyces cerevisiae, the ESCRT-II complex performs a central role in MVB protein sorting and vesicle formation, as it is recruited by the upstream ESCRT-I complex and nucleates assembly of the downstream ESCRT-III complex. Here, we report that the three subunits of human ESCRT-II, EAP20, EAP30, and EAP45, have a number of properties in common with their yeast orthologs. Specifically, EAP45 bound ubiquitin via its N-terminal GRAM-like ubiquitin-binding in EAP45 (GLUE) domain, both EAP45 and EAP30 bound the C-terminal domain of TSG101/ESCRT-I, and EAP20 bound the N-terminal half of CHMP6/ESCRT-III. Consistent with its expected role in MVB vesicle formation, (i) human ESCRT-II localized to endosomal membranes in a VPS4-dependent fashion and (ii) depletion of EAP20/ESCRT-II and CHMP6/ESCRT-III inhibited lysosomal targeting and downregulation of the epidermal growth factor receptor, albeit to a lesser extent than depletion of TSG101/ESCRT-I. Nevertheless, HIV-1 release and infectivity were not reduced by efficient small interfering RNA depletion of EAP20/ESCRT-II or CHMP6/ESCRT-III. These observations indicate that there are probably multiple pathways for protein sorting/MVB vesicle formation in human cells and that HIV-1 does not utilize an ESCRT-II-dependent pathway to leave the cell.
authors.affiliation: Department of Biochemistry, 15 N. Medical Drive East, Room 4100, University of Utah School of Medicine, Salt Lake City, UT 84112-5650, USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Langelier
authors.forename: Uta K
authors.initials: UK
authors.lastname: von Schwedler
authors.forename: Robert D
authors.initials: RD
authors.lastname: Fisher
authors.forename: Ivana
authors.initials: I
authors.lastname: De Domenico
authors.forename: Paul L
authors.initials: PL
authors.lastname: White
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Hill
authors.forename: Jerry
authors.initials: J
authors.lastname: Kaplan
authors.forename: Diane
authors.initials: D
authors.lastname: Ward
authors.forename: Wesley I
authors.initials: WI
authors.lastname: Sundquist
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D015415:Biomarkers; D015374:Biosensing Techniques; D019556:COS Cells; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002522:Chlorocebus aethiops; D004268:DNA-Binding Proteins / Q000378:metabolism; D015536:Down-Regulation; D056827:Endosomal Sorting Complexes Required for Transport; D066246:ErbB Receptors / Q000378:metabolism; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D008958:Models, Molecular; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D025801:Ubiquitin / Q000378:metabolism; D025262:Vacuolar Proton-Translocating ATPases; D033921:Vesicular Transport Proteins; D014771:Virion / Q000378:metabolism
chemical_list: D015415:Biomarkers; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D012097:Repressor Proteins; D025801:Ubiquitin; D033921:Vesicular Transport Proteins; D066246:ErbB Receptors; D000251:Adenosine Triphosphatases; D025262:Vacuolar Proton-Translocating ATPases; D000074183:ATPases Associated with Diverse Cellular Activities; C490305:VPS4A protein, human