A diacidic motif in human immunodeficiency virus type 1 Nef is a novel determinant of binding to AP-2.
A key function of the Nef protein of immunodeficiency viruses is the downregulation of the T-cell and macrophage coreceptor, CD4, from the surfaces of infected cells. CD4 downregulation depends on a conserved (D/E)XXXL(L/I)-type dileucine motif in the C-terminal, flexible loop of Nef, which mediates binding to the clathrin adaptor complexes AP-1, AP-2, and AP-3. We now report the identification of a consensus (D/E)D motif within this loop as a second, conserved determinant of interaction of Nef with AP-2, though not with AP-1 and AP-3. Mutations in this diacidic motif abrogate both AP-2 binding and CD4 downregulation. We also show that a dileucine motif from tyrosinase, both in its native context and in the context of Nef, can bind to AP-2 independently of a diacidic motif. These results thus identify a novel type of AP-2 interaction determinant, support the notion that AP-2 is the key clathrin adaptor for the downregulation of CD4 by Nef, and reveal a previously unrecognized diversity among dileucine sorting signals.
Lindwasser
O Wolf
OW
Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, Building 18T, Room 101, National Institutes of Health, Bethesda, MD 20892, USA. juan@helix.nih.gov
Smith
William J
WJ
Chaudhuri
Rittik
R
Yang
Peter
P
Hurley
James H
JH
Bonifacino
Juan S
JS
D033961:Adaptor Protein Complex 1 / Q000378:metabolism; D033962:Adaptor Protein Complex 2 / Q000378:metabolism*; D033963:Adaptor Protein Complex 3 / Q000378:metabolism; D000595:Amino Acid Sequence; D015497:HIV-1 / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000378:metabolism; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D054311:nef Gene Products, Human Immunodeficiency Virus / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
D033961:Adaptor Protein Complex 1; D033962:Adaptor Protein Complex 2; D033963:Adaptor Protein Complex 3; D050505:Mutant Proteins; D054311:nef Gene Products, Human Immunodeficiency Virus; C514837:nef protein, Human immunodeficiency virus 1