Glutamic Acid Residues in HIV-1 p6 Regulate Virus Budding and Membrane Association of Gag.
The HIV-1 Gag p6 protein regulates the final abscission step of nascent virions from the cell membrane by the action of its two late (L-) domains, which recruit Tsg101 and ALIX, components of the ESCRT system. Even though p6 consists of only 52 amino acids, it is encoded by one of the most polymorphic regions of the HIV-1 gag gene and undergoes various posttranslational modifications including sumoylation, ubiquitination, and phosphorylation. In addition, it mediates the incorporation of the HIV-1 accessory protein Vpr into budding virions. Despite its small size, p6 exhibits an unusually high charge density. In this study, we show that mutation of the conserved glutamic acids within p6 increases the membrane association of Pr55 Gag followed by enhanced polyubiquitination and MHC-I antigen presentation of Gag-derived epitopes, possibly due to prolonged exposure to membrane bound E3 ligases. The replication capacity of the total glutamic acid mutant E0A was almost completely impaired, which was accompanied by defective virus release that could not be rescued by ALIX overexpression. Altogether, our data indicate that the glutamic acids within p6 contribute to the late steps of viral replication and may contribute to the interaction of Gag with the plasma membrane.
Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany. Melanie.Friedrich@viro.med.uni-erlangen.de.
Melanie
M
Friedrich
Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany. Christian.Setz@viro.med.uni-erlangen.de.
Christian
C
Setz
Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany. Friedrich.Hahn@viro.med.uni-erlangen.de.
Friedrich
F
Hahn
Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany. Alina.Matthaei@viro.med.uni-erlangen.de.
Alina
A
Matthaei
Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany. Kirsten.Fraedrich@viro.med.uni-erlangen.de.
Kirsten
K
Fraedrich
Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany. Pia.Rauch@viro.med.uni-erlangen.de.
Pia
P
Rauch
Institute of Biochemistry, Charité Universitätsmedizin-Berlin, Berlin 10117, Germany. Petra.Henklein@charite.de.
Petra
P
Henklein
Department of Otorhinolaryngology, Head and Neck Surgery, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany. maximilian.traxdorf@uk-erlangen.de.
Maximilian
M
Traxdorf
Department of Chemistry and Center for Pharmacy, University of Bergen, Bergen N-5007, Norway. Torgils.Fossen@kj.uib.no.
Torgils
T
Fossen
Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany. Ulrich.Schubert@viro.med.uni-erlangen.de.
Ulrich
U
Schubert
D000595:Amino Acid Sequence; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D056827:Endosomal Sorting Complexes Required for Transport / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D018698:Glutamic Acid / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015658:HIV Infections / Q000378:metabolism / Q000821:virology; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D009154:Mutation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D054875:Ubiquitination; D057074:Virus Release; D014779:Virus Replication; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D056827:Endosomal Sorting Complexes Required for Transport; C117020:PDCD6IP protein, human; D054301:gag Gene Products, Human Immunodeficiency Virus; C083002:p6 gag protein, Human immunodeficiency virus 1; D018698:Glutamic Acid
">l-domains; ALIX; ESCRT; Gag p6; HIV-1; Tsg101; membrane association; ubiquitination; virus budding