Dataset Information

Cdc45p assembles into a complex with Cdc46p/Mcm5p, is required for minichromosome maintenance, and is essential for chromosomal DNA replication.

ABSTRACT: We report the isolation and characterization of CDC45, which encodes a polypeptide of 650 amino acids that is essential for the initiation of chromosomal DNA replication in the budding yeast, Saccharomyces cerevisiae. CDC45 genetically interacts with at least two members of the MCM (minichromosome maintenance) family of replication genes, CDC46 and CDC47, which are proposed to perform a role in restricting initiation of DNA replication to once per cell cycle. Like mutants in several MCM genes, alleles of CDC45 also show a severe minichromosome maintenance defect. Together, these observations imply that Cdc45p performs a role in the control of initiation events at chromosomal replication origins. We investigated this possibility further and present evidence demonstrating that Cdc45p is assembled into complexes with one MCM family member, Cdc46p/Mcm5p. These observations point to a role for Cdc45p in controlling the early steps of chromosomal DNA replication in conjunction with MCM polypeptide complexes. Unlike the MCMs, however, the subcellular localization of Cdc45p does not vary with the cell cycle, making it likely that Cdc45p interacts with MCMs only during the nuclear phase of MCM localization in G1.

SUBMITTER: Hopwood B

PROVIDER: S-EPMC37987 | biostudies-other | 1996 Oct

REPOSITORIES: biostudies-other

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Publications

Cdc45p assembles into a complex with Cdc46p/Mcm5p, is required for minichromosome maintenance, and is essential for chromosomal DNA replication.

Hopwood B B Dalton S S

Proceedings of the National Academy of Sciences of the United States of America 19961001 22

We report the isolation and characterization of CDC45, which encodes a polypeptide of 650 amino acids that is essential for the initiation of chromosomal DNA replication in the budding yeast, Saccharomyces cerevisiae. CDC45 genetically interacts with at least two members of the MCM (minichromosome maintenance) family of replication genes, CDC46 and CDC47, which are proposed to perform a role in restricting initiation of DNA replication to once per cell cycle. Like mutants in several MCM genes, a ...[more]

PMID: 8901577

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Project description:UnlabelledGINS is a key component of the eukaryotic Cdc45-minichromosome maintenance (MCM)-GINS (CMG) complex, which unwinds duplex DNA at the moving replication fork. Archaeal GINS complexes have been shown to stimulate the helicase activity of their cognate MCM mainly by elevating its ATPase activity. Here, we report that GINS from the thermoacidophilic crenarchaeon Sulfolobus solfataricus (SsoGINS) is capable of DNA binding and binds preferentially to single-stranded DNA (ssDNA) over double-stranded DNA (dsDNA). Notably, SsoGINS binds more strongly to dsDNA with a 5' ssDNA tail than to dsDNA with a 3' tail and more strongly to an ssDNA fragment blocked at the 3' end than to one at the 5' end with a biotin-streptavidin (SA) complex, suggesting the ability of the protein complex to slide in a 5'-to-3' direction along ssDNA. DNA-bound SsoGINS enhances DNA binding by SsoMCM. Furthermore, SsoGINS increases the helicase activity of SsoMCM. However, the ATPase activity of SsoMCM is not affected by SsoGINS. Our results suggest that SsoGINS facilitates processive DNA unwinding by SsoMCM by enhancing the binding of the helicase to DNA. We propose that SsoGINS stabilizes the interaction of SsoMCM with the replication fork and moves along with the helicase as the fork progresses.ImportanceGINS is a key component of the eukaryotic Cdc45-MCM-GINS complex, a molecular motor that drives the unwinding of DNA in front of the replication fork. Archaea also encode GINS, which interacts with MCM, the helicase. But how archaeal GINS serves its role remains to be understood. In this study, we show that GINS from the hyperthermophilic archaeon Sulfolobus solfataricus is able to bind to DNA and slide along ssDNA in a 5'-to-3' direction. Furthermore, Sulfolobus GINS enhances DNA binding by MCM, which slides along ssDNA in a 3'-to-5' direction. Taken together, these results suggest that Sulfolobus GINS may stabilize the interaction of MCM with the moving replication fork, facilitating processive DNA unwinding.

Dataset Information

Cdc45p assembles into a complex with Cdc46p/Mcm5p, is required for minichromosome maintenance, and is essential for chromosomal DNA replication.

Publications

Cdc45p assembles into a complex with Cdc46p/Mcm5p, is required for minichromosome maintenance, and is essential for chromosomal DNA replication.

Similar Datasets

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