A NOVEL KINASE-ACTIVITY ASSOCIATED WITH NEF DERIVED FROM NEUROVIRULENT SIMIAN IMMUNODEFICIENCY VIRUS

The Nef proteins of Simian immunodeficiency virus (SIV) and human immu nodeficiency virus (HIV) have been shown to associate with several cel lular kinases. Further, the ability of SIVmac239 Nef to associate with a pal-activated kinase (PAK)-related kinase has been correlated with pathogenic progression to AIDS in rhesus macaques. Because the ability of Nef to associate with the PAK-related kinase is viral isolate depe ndent, we reasoned that viral isolates derived from distinct physiolog ical locations may encode Nef proteins that exhibit distinct kinase as sociation profiles. In this study, we compared kinase activities assoc iated with Nef proteins derived from the prototypic lymphocyte-tropic SIVmac239 and a macrophagetropic, neurovirulent clone, SIV/17E-Fr. Our findings not only support previous studies that have documented the a ssociation of SIVmac239 Nef with a PAK-related kinase and a Nef-associ ated kinase complex (NAKC) but describe a novel serine kinase activity detectable only in conjunction with the Nef protein derived from the neurovirulent clone, SIV/17E-Fr. The latter Nef protein does not assoc iate with PAK, and unlike PAK or NAKC, this novel kinase activity is e nhanced in association with nonmyristoylated forms of Nef and can util ize both ATP and GTP as phosphodonors. We also show that at least one substrate for the kinase is Nef itself and demonstrate that the SIV/17 E-Fr Nef protein is phosphorylated in SIV-infected cells. These result s suggest that the ability to associate with cellular kinases in gener al may be a conserved feature of Nef, but particular kinase/Nef associ ations may evolve with changes in the host environment concomitant wit h viral spread. (C) 1998 Academic Press.