The HIV-1 protein Nef activates the Tec family kinase Btk by stabilizing an intermolecular SH3-SH2 domain interaction

• Published in: Science signaling 2022-09, Vol.15 (752), p.eabn8359-eabn8359
• Main Authors: Aryal, Manish, Lin, David, Regan, Kiera, Du, Shoucheng, Shi, Haibin, Alvarado, John J, Ilina, Tatiana V, Andreotti, Amy H, Smithgall, Thomas E
• Format: Article
• Language: English
• Subjects: Alanine - metabolism; Bruton's tyrosine kinase; Domains; HIV; HIV-1 - metabolism; Human immunodeficiency virus; Humans; Kinases; Myeloid cells; nef Gene Products, Human Immunodeficiency Virus - genetics; nef Gene Products, Human Immunodeficiency Virus - metabolism; Nef protein; Protein-tyrosine kinase; Proteins; Replication; src Homology Domains; src-Family Kinases - genetics; src-Family Kinases - metabolism; Tyrosine; Tyrosine - metabolism
• ISSN: 1945-0877; 1937-9145; 1937-9145
• DOI: 10.1126/scisignal.abn8359

The Nef protein produced by the viruses HIV-1 and SIV drives efficient viral replication partially by inducing constitutive activation of host cell tyrosine kinases, including members of the Src and Tec families. Here, we uncovered the mechanism by which both HIV-1 and SIV Nef enhanced the activity of the Tec family kinase Btk in vitro and in cells. A Nef mutant that could not bind to the SH3 domain of Src family kinases activated Btk to the same extent as did wild-type Nef, demonstrating that Nef activated Src and Tec family kinases by distinct mechanisms. The Btk SH3-SH2 region formed a homodimer requiring the CD loop in the SH2 domain, which was stabilized by the binding of Nef homodimers. Alanine substitution of Pro in the CD loop of the Btk SH2 domain destabilized SH3-SH2 dimers, abolished the interaction with Nef, and prevented activation by Nef in vitro. In cells, Nef stabilized and activated wild-type but not P327A Btk homodimers at the plasma membrane. These data reveal that the interaction with Nef stabilizes Btk dimers through the SH3-SH2 interface to promote kinase activity and show that the HIV-1 Nef protein evolved distinct mechanisms to activate Src and Tec family tyrosine kinases to enhance viral replication.