Herpes Simplex Virus Type 1 Single Strand DNA Binding Protein and Helicase/Primase Complex Disable Cellular ATR Signaling

PLoS Pathogens

Kareem N. Mohni¹  Samantha Smith¹  Alexander R. Dee¹  Sandra K. Weller¹  April J. Schumacher¹ 

[1] Department of Molecular, Microbial and Structural Biology and the Molecular Biology and Biochemistry Graduate Program, University of Connecticut Health Center, Farmington, Connecticut, United States of America

关键词: DNA damage;    DNA replication;    Signal inhibition;    Phosphorylation;    Vero cells;    Viral replication;    DNA-binding proteins;    Cell signaling;   

DOI  :  10.1371/journal.ppat.1003652

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Herpes Simplex Virus type 1 (HSV-1) has evolved to disable the cellular DNA damage response kinase, ATR. We have previously shown that HSV-1-infected cells are unable to phosphorylate the ATR substrate Chk1, even under conditions in which replication forks are stalled. Here we report that the HSV-1 single stranded DNA binding protein (ICP8), and the helicase/primase complex (UL8/UL5/UL52) form a nuclear complex in transfected cells that is necessary and sufficient to disable ATR signaling. This complex localizes to sites of DNA damage and colocalizes with ATR/ATRIP and RPA, but under these conditions, the Rad9-Rad1-Hus1 checkpoint clamp (9-1-1) do not. ATR is generally activated by substrates that contain ssDNA adjacent to dsDNA, and previous work from our laboratory has shown that ICP8 and helicase/primase also recognize this substrate. We suggest that these four viral proteins prevent ATR activation by binding to the DNA substrate and obstructing loading of the 9-1-1 checkpoint clamp. Exclusion of 9-1-1 prevents recruitment of TopBP1, the ATR kinase activator, and thus effectively disables ATR signaling. These data provide the first example of viral DNA replication proteins obscuring access to a DNA substrate that would normally trigger a DNA damage response and checkpoint signaling. This unusual mechanism used by HSV suggests that it may be possible to inhibit ATR signaling by preventing recruitment of the 9-1-1 clamp and TopBP1.

【 授权许可】

CC BY