title: Late domain-dependent inhibition of equine infectious anemia virus budding.
abstract: The Gag proteins of a number of different retroviruses contain late or L domains that promote the release of virions from the plasma membrane. Three types of L domains have been identified to date: Pro-Thr-Ala-Pro (PTAP), Pro-Pro-X-Tyr, and Tyr-Pro-Asp-Leu. It has previously been demonstrated that overexpression of the N-terminal, E2-like domain of the endosomal sorting factor TSG101 (TSG-5') inhibits human immunodeficiency virus type 1 (HIV-1) release but does not affect the release of the PPPY-containing retrovirus murine leukemia virus (MLV), whereas overexpression of the C-terminal portion of TSG101 (TSG-3') potently disrupts both HIV-1 and MLV budding. In addition, it has been reported that, while the release of a number of retroviruses is disrupted by proteasome inhibitors, equine infectious anemia virus (EIAV) budding is not affected by these agents. In this study, we tested the ability of TSG-5', TSG-3', and full-length TSG101 (TSG-F) overexpression, a dominant negative form of the AAA ATPase Vps4, and proteasome inhibitors to disrupt the budding of EIAV particles bearing each of the three types of L domain. The results indicate that (i) inhibition by TSG-5' correlates with dependence on PTAP; (ii) the release of wild-type EIAV (EIAV/WT) is insensitive to TSG-3', whereas this C-terminal TSG101 fragment potently impairs the budding of EIAV when it is rendered PTAP or PPPY dependent; (iii) budding of all EIAV clones is blocked by dominant negative Vps4; and (iv) EIAV/WT release is not impaired by proteasome inhibitors, while EIAV/PTAP and EIAV/PPPY release is strongly disrupted by these compounds. These findings highlight intriguing similarities and differences in host factor utilization by retroviral L domains and suggest that the insensitivity of EIAV to proteasome inhibitors is conferred by the L domain itself and not by determinants in Gag outside the L domain.
authors.affiliation: Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0460, USA.
authors.forename: Miranda
authors.initials: M
authors.lastname: Shehu-Xhilaga
authors.forename: Sherimay
authors.initials: S
authors.lastname: Ablan
authors.forename: Dimiter G
authors.initials: DG
authors.lastname: Demirov
authors.forename: Chaoping
authors.initials: C
authors.lastname: Chen
authors.forename: Ronald C
authors.initials: RC
authors.lastname: Montelaro
authors.forename: Eric O
authors.initials: EO
authors.lastname: Freed
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D020816:Amino Acid Motifs; D000818:Animals; D002460:Cell Line; D003546:Cysteine Endopeptidases; D015967:Gene Expression Regulation, Viral; D015683:Gene Products, gag / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D004860:Infectious Anemia Virus, Equine / Q000737:chemistry / Q000254:growth & development* / Q000472:pathogenicity; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors*; D011480:Protease Inhibitors / Q000494:pharmacology*; D046988:Proteasome Endopeptidase Complex; D014162:Transfection; D014771:Virion / Q000235:genetics / Q000378:metabolism*
chemical_list: D015683:Gene Products, gag; D009097:Multienzyme Complexes; D011480:Protease Inhibitors; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D000251:Adenosine Triphosphatases