Replication Protein A (RPA) Phosphorylation Prevents RPA Association with Replication Centers

AUTOR(ES)

Vassin, Vitaly M.

FONTE

American Society for Microbiology

RESUMO

Mammalian replication protein A (RPA) undergoes DNA damage-dependent phosphorylation at numerous sites on the N terminus of the RPA2 subunit. To understand the functional significance of RPA phosphorylation, we expressed RPA2 variants in which the phosphorylation sites were converted to aspartate (RPA2D) or alanine (RPA2A). Although RPA2D was incorporated into RPA heterotrimers and supported simian virus 40 DNA replication in vitro, the RPA2D mutant was selectively unable to associate with replication centers in vivo. In cells containing greatly reduced levels of endogenous RPA2, RPA2D again did not localize to replication sites, indicating that the defect in supporting chromosomal DNA replication is not due to competition with the wild-type protein. Use of phosphospecific antibodies demonstrated that endogenous hyperphosphorylated RPA behaves similarly to RPA2D. In contrast, under DNA damage or replication stress conditions, RPA2D, like RPA2A and wild-type RPA2, was competent to associate with DNA damage foci as determined by colocalization with γ-H2AX. We conclude that RPA2 phosphorylation prevents RPA association with replication centers in vivo and potentially serves as a marker for sites of DNA damage.

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