Human immunodeficiency virus type 1 Vpr-binding protein VprBP, a WD40 protein associated with the DDB1-CUL4 E3 ubiquitin ligase, is essential for DNA replication and embryonic development.
Damaged DNA binding protein 1, DDB1, bridges an estimated 90 or more WD40 repeats (DDB1-binding WD40, or DWD proteins) to the CUL4-ROC1 catalytic core to constitute a potentially large number of E3 ligase complexes. Among these DWD proteins is the human immunodeficiency virus type 1 (HIV-1) Vpr-binding protein VprBP, whose cellular function has yet to be characterized but has recently been found to mediate Vpr-induced G(2) cell cycle arrest. We demonstrate here that VprBP binds stoichiometrically with DDB1 through its WD40 domain and through DDB1 to CUL4A, subunits of the COP9/signalsome, and DDA1. The steady-state level of VprBP remains constant during interphase and decreases during mitosis. VprBP binds to chromatin in a DDB1-independent and cell cycle-dependent manner, increasing from early S through G(2) before decreasing to undetectable levels in mitotic and G(1) cells. Silencing VprBP reduced the rate of DNA replication, blocked cells from progressing through the S phase, and inhibited proliferation. VprBP ablation in mice results in early embryonic lethality. Conditional deletion of the VprBP gene in mouse embryonic fibroblasts results in severely defective progression through S phase and subsequent apoptosis. Our studies identify a previously unknown function of VprBP in S-phase progression and suggest the possibility that HIV-1 Vpr may divert an ongoing chromosomal replication activity to facilitate viral replication.
McCall
Chad M
CM
Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, USA.
Miliani de Marval
Paula L
PL
Chastain
Paul D
PD
Jackson
Sarah C
SC
He
Yizhou J
YJ
Kotake
Yojiro
Y
Cook
Jeanette Gowen
JG
Xiong
Yue
Y
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000502:physiology; D002478:Cells, Cultured; D002843:Chromatin / Q000378:metabolism; D044842:Cullin Proteins / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000502:physiology*; D005260:Female; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases; D034622:RNA Interference; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054325:vpr Gene Products, Human Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism
C114234:CUL4A protein, human; D002352:Carrier Proteins; D002843:Chromatin; D044842:Cullin Proteins; C091435:DDB1 protein, human; D004268:DNA-Binding Proteins; C479529:RBX1 protein, human; 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