title: Binding of HIV-1 Vpr protein to the human homolog of the yeast DNA repair protein RAD23 (hHR23A) requires its xeroderma pigmentosum complementation group C binding (XPCB) domain as well as the ubiquitin-associated 2 (UBA2) domain.
abstract: The human homolog of the yeast DNA repair protein RAD23, hHR23A, has been found previously to interact with the human immunodeficiency virus, type 1 accessory protein Vpr. hHR23A is a modular protein containing an N-terminal ubiquitin-like (UBL) domain and two ubiquitin-associated domains (UBA1 and UBA2) separated by a xeroderma pigmentosum complementation group C binding (XPCB) domain. All domains are connected by flexible linkers. hHR23A binds ubiquitinated proteins and acts as a shuttling factor to the proteasome. Here, we show that hHR23A utilizes both the UBA2 and XPCB domains to form a stable complex with Vpr, linking Vpr directly to cellular DNA repair pathways and their probable exploitation by the virus. Detailed structural mapping of the Vpr contacts on hHR23A, by NMR, revealed substantial contact surfaces on the UBA2 and XPCB domains. In addition, Vpr binding disrupts an intramolecular UBL-UBA2 interaction. We also show that Lys-48-linked di-ubiquitin, when binding to UBA1, does not release the bound Vpr from the hHR23A-Vpr complex. Instead, a ternary hHR23A·Vpr·di-Ub(K48) complex is formed, indicating that Vpr does not necessarily abolish hHR23A-mediated shuttling to the proteasome.
authors: From the Department of Structural Biology and Pittsburgh Center for HIV-Host Protein Interactions, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania 15261.
authors: Jinwon
authors: J
authors: Jung
authors: In-Ja L
authors: IJ
authors: Byeon
authors: Maria
authors: M
authors: DeLucia
authors: Leonardus M I
authors: LM
authors: Koharudin
authors: Jinwoo
authors: J
authors: Ahn
authors: Angela M
authors: AM
authors: Gronenborn
mesh_terms: D001665:Binding Sites; D004260:DNA Repair; D045643:DNA Repair Enzymes / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D015658:HIV Infections / Q000378:metabolism / Q000821:virology*; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D017434:Protein Structure, Tertiary; D044764:Ubiquitin-Activating Enzymes / Q000737:chemistry / Q000378:metabolism*; D054875:Ubiquitination; D054325:vpr Gene Products, Human Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; C470301:UBA2 protein, human; D054325:vpr Gene Products, Human Immunodeficiency Virus; C514912:vpr protein, Human immunodeficiency virus 1; C086985:RAD23A protein, human; C086984:XPC protein, human; D044764:Ubiquitin-Activating Enzymes; D045643:DNA Repair Enzymes
keywords: Base Excision Repair; Binding; HIV-1; NMR; Protein-Protein Interactions; UBA2; Ubiquitination; Vpr; XPCB; hHR23A