Efficient Parvovirus Replication Requires CRL4Cdt2-Targeted Depletion of p21 to Prevent Its Inhibitory Interaction with PCNA

Richard O Adeyemi,Matthew S Fuller,David J Pintel,David Ornelles

doi:10.1371/journal.ppat.1004055

Richard O Adeyemi, Matthew S Fuller + Show 2 more

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https://doi.org/10.1371/journal.ppat.1004055

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Journal: PLoS Pathogens	Publication Date: Apr 3, 2014
Citations: 16	License type: CC BY 4.0

Affiliation: University of Missouri

Abstract

Infection by the autonomous parvovirus minute virus of mice (MVM) induces a vigorous DNA damage response in host cells which it utilizes for its efficient replication. Although p53 remains activated, p21 protein levels remain low throughout the course of infection. We show here that efficient MVM replication required the targeting for degradation of p21 during this time by the CRL4Cdt2 E3-ubiquitin ligase which became re-localized to MVM replication centers. PCNA provides a molecular platform for substrate recognition by the CRL4Cdt2 E3-ubiquitin ligase and p21 targeting during MVM infection required its interaction both with Cdt2 and PCNA. PCNA is also an important co-factor for MVM replication which can be antagonized by p21 in vitro. Expression of a stable p21 mutant that retained interaction with PCNA inhibited MVM replication, while a stable p21 mutant which lacked this interaction did not. Thus, while interaction with PCNA was important for targeting p21 to the CRL4Cdt2 ligase re-localized to MVM replication centers, efficient viral replication required subsequent depletion of p21 to abrogate its inhibition of PCNA.

Highlights

Minute Virus of Mice (MVM) is an autonomously-replicating parvovirus which induces a DNA damage response resulting in substantial p53 activation which persists throughout the course of viral replication [1]. p53 is a well-established activator of p21WAF1/Cip1 expression
P21 has been shown to be an effective inhibitor of the DNA polymerase d cofactor PCNA [5,6,7], and it has been shown to inhibit MVM replication in vitro [8]. p21 depletion during MVM infection was shown to be proteasomally mediated, suggesting that an E3 ubiquitin ligase was involved in targeting p21 for degradation [2]
The Cullin-RING Ligase (CRL) CRL4Cdt2 consists of the scaffold protein Cullin 4 and the homo-trimeric protein DDB1 which serves as an adaptor for the putative substrate recognition protein Cdt2

Summary

Introduction

Minute Virus of Mice (MVM) is an autonomously-replicating parvovirus which induces a DNA damage response resulting in substantial p53 activation which persists throughout the course of viral replication [1]. p53 is a well-established activator of p21WAF1/Cip (hereafter referred to as p21) expression. The Cullin-RING Ligase (CRL) CRL4Cdt consists of the scaffold protein Cullin 4 and the homo-trimeric protein DDB1 which serves as an adaptor for the putative substrate recognition protein Cdt. The Cullin-RING Ligase (CRL) CRL4Cdt consists of the scaffold protein Cullin 4 and the homo-trimeric protein DDB1 which serves as an adaptor for the putative substrate recognition protein Cdt2 This ligase has been shown to program the ubiquitination and subsequent degradation of p21 in response to DNA damaging agents such as UV treatment in order to ensure low p21 levels during S-phase [10,11,12]. Upon DNA damage or S-phase entry CRL4Cdt is recruited to chromatin via PCNA interaction where it targets substrate proteins for degradation [13]

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