Cell cycle-dependent dynamic association of cyclin/Cdk complexes with human DNA replication proteins

AUTOR(ES)

Frouin, Isabelle

FONTE

Oxford University Press

RESUMO

We have previously described the isolation of a replication competent (RC) complex from calf thymus, containing DNA polymerase α, DNA polymerase δ and replication factor C. Here, we describe the isolation of the RC complex from nuclear extracts of synchronized HeLa cells, which contains DNA replication proteins associated with cell-cycle regulation factors like cyclin A, cyclin B1, Cdk2 and Cdk1. In addition, it contains a kinase activity and DNA polymerase activities able to switch from a distributive to a processive mode of DNA synthesis, which is dependent on proliferating cell nuclear antigen. In vivo cross-linking of proteins to DNA in synchronized HeLa cells demonstrates the association of this complex to chromatin. We show a dynamic association of cyclins/Cdks with the RC complex during the cell cycle. Indeed, cyclin A and Cdk2 associated with the complex in S phase, and cyclin B1 and Cdk1 were present exclusively in G2/M phase, suggesting that the activity, as well the localization, of the RC complex might be regulated by specific cyclin/Cdk complexes.

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