Adeyemi Richard O, Fuller Matthew S, Pintel David J
Department of Molecular Microbiology and Immunology, C.S. Bond Life Sciences Center, University of Missouri-Columbia, School of Medicine, Columbia, Missouri, United States of America.
PLoS Pathog. 2014 Apr 3;10(4):e1004055. doi: 10.1371/journal.ppat.1004055. eCollection 2014 Apr.
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.
小鼠自主细小病毒（MVM）感染会在宿主细胞中引发强烈的DNA损伤反应，而病毒利用这种反应进行高效复制。尽管p53一直处于激活状态，但在整个感染过程中p21蛋白水平一直很低。我们在此表明，MVM的高效复制需要在这段时间内通过CRL4Cdt2 E3泛素连接酶将p21靶向降解，该连接酶会重新定位于MVM复制中心。PCNA为CRL4Cdt2 E3泛素连接酶识别底物提供了一个分子平台，并且在MVM感染期间将p21靶向需要其与Cdt2和PCNA两者相互作用。PCNA也是MVM复制的一个重要辅助因子，在体外它可被p21拮抗。表达与PCNA保持相互作用的稳定p21突变体抑制了MVM复制，而缺乏这种相互作用的稳定p21突变体则没有。因此，虽然与PCNA的相互作用对于将p21靶向重新定位于MVM复制中心的CRL4Cdt2连接酶很重要，但高效的病毒复制需要随后消耗p21以消除其对PCNA的抑制作用。
