Phosphorylation of MCM4 at sites inactivating DNA helicase activity of the MCM4-MCM6-MCM7 complex during Epstein-Barr virus productive replication

Ayumi Kudoh, Tohru Daikoku, Yukio Ishimi, Yasushi Kawaguchi, Noriko Shirata, Satoko Iwahori, Hiroki Isomura, Tatsuya Tsurumi

Research output: Contribution to journalArticlepeer-review

48 Citations (Scopus)

Abstract

Induction of Epstein-Barr virus (EBV) lytic replication blocks chromosomal DNA replication notwithstanding an S-phase-like cellular environment with high cyclin-dependent kinase (CDK) activity. We report here that the phosphorylated form of MCM4, a subunit of the MCM complex essential for chromosomal DNA replication, increases with progression of lytic replication, Thr-19 and Thr-110 being CDK2/CDK1 targets whose phosphorylation inactivates MCM4-MCM6-MCM7 (MCM4-6-7) complex-associated DNA helicase. Expression of EBV-encoded protein kinase (EBV-PK) in HeLa cells caused phosphorylation of these sites on MCM4, leading to cell growth arrest. In vitro, the sites of MCM4 of the MCM4-6-7 hexamer were confirmed to be phosphorylated with EBV-PK, with the same loss of helicase activity as with CDK2/cyclin A. Introducing mutations in the N-terminal six Ser and Thr residues of MCM4 reduced the inhibition by CDK2/cydin A, while EBV-PK inhibited the helicase activities of both wild-type and mutant MCM4-6-7 hexamers, probably since EBV-PK can phosphorylate MCM6 and another site(s) of MCM4 in addition to the N-terminal residues. Therefore, phosphorylation of the MCM complex by redundant actions of CDK and EBV-PK during lytic replication might provide one mechanism to block chromosomal DNA replication in the infected cells through inactivation of DNA unwinding by the MCM4-6-7 complex.

Original languageEnglish
Pages (from-to)10064-10072
Number of pages9
JournalJournal of Virology
Volume80
Issue number20
DOIs
Publication statusPublished - 10-2006
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Immunology
  • Insect Science
  • Virology

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