Phosphorylation of human Fen1 by cyclin-dependent kinase modulates its role in replication fork regulation.

Cyclin-dependent kinase (Cdk) Cdk1-Cyclin A can phosphorylate Flap endonuclease 1 (Fen1), a key-enzyme of the DNA replication machinery, in late S phase. Cdk1-cyclin A forms a complex in vitro and in vivo with Fen1. Furthermore, Fen1 phosphorylation is detected in vivo and depends upon Cdks activity. As a functional consequence ...
of phosphorylation by Cdk1-Cyclin A in vitro, endo- and exonuclease activities of Fen1 are reduced whereas its DNA binding is not affected. Moreover, phosphorylation of Fen1 by Cdk1-Cyclin A abrogates its proliferating cell nuclear antigen (PCNA) binding thus preventing stimulation of Fen1 by PCNA. Concomitantly, human cells expressing the S187A mutant defective for Cdk1-Cyclin A phosphorylation accumulate in S phase consistent with a failure in cell cycle regulation through DNA replication. Our results suggest a novel regulatory role of Cdks onto the end of S phase by targeting directly a key enzyme involved in DNA replication.
Mesh Terms:
Adenosine Triphosphate, CDC2 Protein Kinase, CDC2-CDC28 Kinases, Cyclin A, Cyclin-Dependent Kinase 2, Cyclin-Dependent Kinases, DNA, DNA Replication, Endodeoxyribonucleases, Flap Endonucleases, Hela Cells, Humans, Phosphorylation, Proliferating Cell Nuclear Antigen, Protein-Serine-Threonine Kinases, S Phase
Oncogene
Date: Jul. 10, 2003
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