GINS and Sld3 compete with one another for Mcm2-7 and Cdc45 binding.

Sld3 is essential for the initiation of DNA replication, but Sld3 does not travel with a replication fork. GINS binds to Cdc45 and Mcm2-7 to form the replication fork helicase in eukaryotes. We purified Sld3, Cdc45, GINS, and Mcm2-7 and studied their interaction and assembly into complexes. Sld3 binds tightly ...
to Cdc45 in the presence or absence of cyclin-dependent kinase activity. Furthermore, Sld3 binds tightly to the Mcm2-7 complex, and a ternary complex forms among Cdc45, Mcm2-7, and Sld3, with a 1:1:1 stoichiometry (CMS complex). GINS binds directly to Mcm2-7, and GINS competes with Sld3 for Mcm2-7 binding. GINS also binds directly to Cdc45, and GINS competes with Sld3 for Cdc45 binding. Cdc45, Mcm2-7, and GINS form a ternary complex with a stoichiometry of 1:1:1 (CMG complex). Size exclusion data reveal that when Sld3, Cdc45, Mcm2-7, and GINS are added together, the result is a mixture of CMS and CMG complexes. The data suggest that GINS and Sld3 compete with one another for Mcm2-7 and Cdc45 binding. Our results are consistent with a model wherein GINS trades places with Sld3 at a replication origin, contributing to the activation of the replication fork helicase.
Mesh Terms:
Binding, Competitive, Cell Cycle, Cell Cycle Proteins, Chromosomal Proteins, Non-Histone, DNA Replication, DNA-Binding Proteins, Gene Expression Regulation, Fungal, Glutathione Transferase, Nuclear Proteins, Protein Binding, Replication Origin, Ribonucleoprotein, U4-U6 Small Nuclear, Ribonucleoprotein, U5 Small Nuclear, Saccharomyces cerevisiae Proteins, Saccharomycetales
J. Biol. Chem.
Date: Apr. 22, 2011
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