title: Adenovirus 12 E4orf6 inhibits ATR activation by promoting TOPBP1 degradation.
abstract: Activation of the cellular DNA damage response is detrimental to adenovirus (Ad) infection. Ad has therefore evolved a number of strategies to inhibit ATM- and ATR-dependent signaling pathways during infection. Recent work suggests that the Ad5 E4orf3 protein prevents ATR activation through its ability to mislocalize the MRN complex. Here we provide evidence to indicate that Ad12 has evolved a different strategy from Ad5 to inhibit ATR. We show that Ad12 utilizes a CUL2/RBX1/elongin C-containing ubiquitin ligase to promote the proteasomal degradation of the ATR activator protein topoisomerase-IIbeta-binding protein 1 (TOPBP1). Ad12 also uses this complex to degrade p53 during infection, in contrast to Ad5, which requires a CUL5-based ubiquitin ligase. Although Ad12-mediated degradation of p53 is dependent upon both E1B-55K and E4orf6, Ad12-mediated degradation of TOPBP1 is solely dependent on E4orf6. We propose that Ad12 E4orf6 has two principal activities: to recruit the CUL2-based ubiquitin ligase and to act as substrate receptor for TOPBP1. In support of the idea that Ad12 E4orf6 specifically prevents ATR activation during infection by targeting TOPBP1 for degradation, we demonstrate that Ad12 E4orf6 can inhibit the ATR-dependent phosphorylation of CHK1 in response to replication stress. Taken together, these data provide insights into how Ad modulates ATR signaling pathways during infection.
authors.affiliation: School of Cancer Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom. andrew.blackford@imm.ox.ac.uk
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Blackford
authors.forename: Rakesh N
authors.initials: RN
authors.lastname: Patel
authors.forename: Natalie A
authors.initials: NA
authors.lastname: Forrester
authors.forename: Kathrin
authors.initials: K
authors.lastname: Theil
authors.forename: Peter
authors.initials: P
authors.lastname: Groitl
authors.forename: Grant S
authors.initials: GS
authors.lastname: Stewart
authors.forename: A Malcolm R
authors.initials: AM
authors.lastname: Taylor
authors.forename: Iain M
authors.initials: IM
authors.lastname: Morgan
authors.forename: Thomas
authors.initials: T
authors.lastname: Dobner
authors.forename: Roger J A
authors.initials: RJ
authors.lastname: Grand
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Turnell
mesh_terms: D000256:Adenoviridae / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D017501:Adenovirus E1B Proteins / Q000235:genetics / Q000378:metabolism; D064007:Ataxia Telangiectasia Mutated Proteins; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D000071877:Checkpoint Kinase 1; D044842:Cullin Proteins / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D000075065:Elongin; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D018613:Microscopy, Confocal; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D017501:Adenovirus E1B Proteins; C105153:CUL2 protein, human; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D044842:Cullin Proteins; D004268:DNA-Binding Proteins; C121517:E4orf4 protein, adenovirus; C000616395:ELOC protein, human; D000075065:Elongin; D009687:Nuclear Proteins; C479529:RBX1 protein, human; C110513:TOPBP1 protein, human; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D014764:Viral Proteins; D044767:Ubiquitin-Protein Ligases; D011494:Protein Kinases; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases; D046988:Proteasome Endopeptidase Complex