title: HIV-1 Vpr loads uracil DNA glycosylase-2 onto DCAF1, a substrate recognition subunit of a cullin 4A-ring E3 ubiquitin ligase for proteasome-dependent degradation.
abstract: The human immunodeficiency virus type 1 (HIV-1) accessory protein, Vpr, interacts with several host cellular proteins including uracil DNA glycosylase-2 (UNG2) and a cullin-RING E3 ubiquitin ligase assembly (CRL4(DCAF1)). The ligase is composed of cullin 4A (CUL4A), RING H2 finger protein (RBX1), DNA damage-binding protein 1 (DDB1), and a substrate recognition subunit, DDB1- and CUL4-associated factor 1 (DCAF1). Here we show that recombinant UNG2 specifically interacts with Vpr, but not with Vpx of simian immunodeficiency virus, forming a heterotrimeric complex with DCAF1 and Vpr in vitro as well as in vivo. Using reconstituted CRL4(DCAF1) and CRL4(DCAF1-Vpr) E3 ubiquitin ligases in vitro reveals that UNG2 ubiquitination (ubiquitylation) is facilitated by Vpr. Co-expression of DCAF1 and Vpr causes down-regulation of UNG2 in a proteasome-dependent manner, with Vpr mutants that are defective in UNG2 or DCAF1 binding abrogating this effect. Taken together, our results show that the CRL4(DCAF1) E3 ubiquitin ligase can be subverted by Vpr to target UNG2 for degradation.
authors.affiliation: Department of Structural Biology, University of Pittsburgh School of Medicine and Cancer Institute, Pittsburgh, Pennsylvania 15260, USA. jia12@pitt.edu
authors.forename: Jinwoo
authors.initials: J
authors.lastname: Ahn
authors.forename: Thomas
authors.initials: T
authors.lastname: Vu
authors.forename: Zach
authors.initials: Z
authors.lastname: Novince
authors.forename: Jennifer
authors.initials: J
authors.lastname: Guerrero-Santoro
authors.forename: Vesna
authors.initials: V
authors.lastname: Rapic-Otrin
authors.forename: Angela M
authors.initials: AM
authors.lastname: Gronenborn
mesh_terms: D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D044842:Cullin Proteins / Q000235:genetics / Q000378:metabolism; D045647:DNA Glycosylases / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D015658:HIV Infections / Q000235:genetics / Q000378:metabolism* / Q000821:virology; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism; D054875:Ubiquitination; D054325:vpr Gene Products, Human Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism*
chemical_list: C114234:CUL4A protein, human; D002352:Carrier Proteins; D044842:Cullin Proteins; D054325:vpr Gene Products, Human Immunodeficiency Virus; C514912:vpr protein, Human immunodeficiency virus 1; D044767:Ubiquitin-Protein Ligases; C530533:DCAF1 protein, human; D017346:Protein Serine-Threonine Kinases; C492570:CCNO protein, human; D045647:DNA Glycosylases; D046988:Proteasome Endopeptidase Complex