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In vertebrates, MCM2-7 and Cdc45 are required for DNA replication initiation, but it is unknown whether they are also required for elongation, as in yeast. Moreover, although MCM2-7 is a prime candidate for the eukaryotic replicative DNA helicase, a demonstration that MCM2-7 unwinds DNA during replication is lacking. Here, we use Xenopus egg extracts to investigate the roles of MCM7 and Cdc45 in DNA replication. A fragment of the retinoblastoma protein, Rb(1-400), was used to neutralize MCM7, and antibodies were used to neutralize Cdc45. When added immediately after origin unwinding, or after significant DNA synthesis, both inhibitors blocked further DNA replication, indicating that MCM7 and Cdc45 are required throughout replication elongation in vertebrates. We next exploited the fact that inhibition of DNA polymerase by aphidicolin causes extensive chromosome unwinding, likely due to uncoupling of the replicative DNA helicase. Strikingly, Rb(1-400) and Cdc45 antibodies both abolished unwinding by the uncoupled helicase. These results provide new support for the model that MCM2-7 is the replicative DNA helicase, and they indicate that Cdc45 functions as a helicase co-factor.
Aparicio,
Components and dynamics of DNA replication complexes in S. cerevisiae: redistribution of MCM proteins and Cdc45p during S phase.
1997, Pubmed
Aparicio,
Components and dynamics of DNA replication complexes in S. cerevisiae: redistribution of MCM proteins and Cdc45p during S phase.
1997,
Pubmed
Avni,
Active localization of the retinoblastoma protein in chromatin and its response to S phase DNA damage.
2003,
Pubmed
Bell,
DNA replication in eukaryotic cells.
2002,
Pubmed
Blow,
Initiation of DNA replication in nuclei and purified DNA by a cell-free extract of Xenopus eggs.
1986,
Pubmed
,
Xenbase
Chong,
A double-hexamer archaeal minichromosome maintenance protein is an ATP-dependent DNA helicase.
2000,
Pubmed
Dasso,
Completion of DNA replication is monitored by a feedback system that controls the initiation of mitosis in vitro: studies in Xenopus.
1990,
Pubmed
,
Xenbase
Edwards,
MCM2-7 complexes bind chromatin in a distributed pattern surrounding the origin recognition complex in Xenopus egg extracts.
2002,
Pubmed
,
Xenbase
Fletcher,
The structure and function of MCM from archaeal M. Thermoautotrophicum.
2003,
Pubmed
Gladden,
The cyclin D1-dependent kinase associates with the pre-replication complex and modulates RB.MCM7 binding.
2003,
Pubmed
Grosse,
The primase activity of DNA polymerase alpha from calf thymus.
1985,
Pubmed
Harvey,
Metazoan origin selection: origin recognition complex chromatin binding is regulated by CDC6 recruitment and ATP hydrolysis.
2003,
Pubmed
Hua,
Identification of a preinitiation step in DNA replication that is independent of origin recognition complex and cdc6, but dependent on cdk2.
1998,
Pubmed
,
Xenbase
Ishimi,
Biochemical function of mouse minichromosome maintenance 2 protein.
1998,
Pubmed
Jares,
Xenopus cdc7 function is dependent on licensing but not on XORC, XCdc6, or CDK activity and is required for XCdc45 loading.
2000,
Pubmed
,
Xenbase
Kamitori,
Crystal structure of the 2:1 complex between d(GAAGCTTC) and the anticancer drug actinomycin D.
1992,
Pubmed
Kanemaki,
Functional proteomic identification of DNA replication proteins by induced proteolysis in vivo.
2003,
Pubmed
Kaplan,
Mcm4,6,7 uses a "pump in ring" mechanism to unwind DNA by steric exclusion and actively translocate along a duplex.
2003,
Pubmed
Krude,
Human replication proteins hCdc21, hCdc46 and P1Mcm3 bind chromatin uniformly before S-phase and are displaced locally during DNA replication.
1996,
Pubmed
,
Xenbase
Kubota,
A novel ring-like complex of Xenopus proteins essential for the initiation of DNA replication.
2003,
Pubmed
,
Xenbase
Labib,
Uninterrupted MCM2-7 function required for DNA replication fork progression.
2000,
Pubmed
Labib,
Is the MCM2-7 complex the eukaryotic DNA replication fork helicase?
2001,
Pubmed
Lan,
DNA damage invokes mismatch repair-dependent cyclin D1 attenuation and retinoblastoma signaling pathways to inhibit CDK2.
2002,
Pubmed
Lee,
Isolation and characterization of various complexes of the minichromosome maintenance proteins of Schizosaccharomyces pombe.
2000,
Pubmed
Mahbubani,
Cell cycle regulation of the replication licensing system: involvement of a Cdk-dependent inhibitor.
1997,
Pubmed
,
Xenbase
Masuda,
CDK- and Cdc45-dependent priming of the MCM complex on chromatin during S-phase in Xenopus egg extracts: possible activation of MCM helicase by association with Cdc45.
2003,
Pubmed
,
Xenbase
Michael,
Activation of the DNA replication checkpoint through RNA synthesis by primase.
2000,
Pubmed
,
Xenbase
Mimura,
Central role for cdc45 in establishing an initiation complex of DNA replication in Xenopus egg extracts.
2000,
Pubmed
,
Xenbase
Mimura,
Xenopus Cdc45-dependent loading of DNA polymerase alpha onto chromatin under the control of S-phase Cdk.
1998,
Pubmed
,
Xenbase
Méndez,
Perpetuating the double helix: molecular machines at eukaryotic DNA replication origins.
2003,
Pubmed
,
Xenbase
Prokhorova,
DNA replication of mitotic chromatin in Xenopus egg extracts.
2003,
Pubmed
,
Xenbase
Romanowski,
XMCM7, a novel member of the Xenopus MCM family, interacts with XMCM3 and colocalizes with it throughout replication.
1996,
Pubmed
,
Xenbase
Rowles,
Changes in association of the Xenopus origin recognition complex with chromatin on licensing of replication origins.
1999,
Pubmed
,
Xenbase
Sherr,
Cancer cell cycles.
1996,
Pubmed
Shimada,
ORC and the intra-S-phase checkpoint: a threshold regulates Rad53p activation in S phase.
2002,
Pubmed
Sterner,
Negative regulation of DNA replication by the retinoblastoma protein is mediated by its association with MCM7.
1998,
Pubmed
,
Xenbase
Tada,
Repression of origin assembly in metaphase depends on inhibition of RLF-B/Cdt1 by geminin.
2001,
Pubmed
,
Xenbase
Takayama,
GINS, a novel multiprotein complex required for chromosomal DNA replication in budding yeast.
2003,
Pubmed
Tanaka,
Association of RPA with chromosomal replication origins requires an Mcm protein, and is regulated by Rad53, and cyclin- and Dbf4-dependent kinases.
1998,
Pubmed
Tercero,
DNA synthesis at individual replication forks requires the essential initiation factor Cdc45p.
2000,
Pubmed
Todorov,
A human nuclear protein with sequence homology to a family of early S phase proteins is required for entry into S phase and for cell division.
1994,
Pubmed
Waga,
The DNA replication fork in eukaryotic cells.
1998,
Pubmed
Walter,
Initiation of eukaryotic DNA replication: origin unwinding and sequential chromatin association of Cdc45, RPA, and DNA polymerase alpha.
2000,
Pubmed
,
Xenbase
Walter,
Evidence for sequential action of cdc7 and cdk2 protein kinases during initiation of DNA replication in Xenopus egg extracts.
2000,
Pubmed
,
Xenbase
Walter,
Regulation of replicon size in Xenopus egg extracts.
1997,
Pubmed
,
Xenbase
Walter,
Regulated chromosomal DNA replication in the absence of a nucleus.
1998,
Pubmed
,
Xenbase
Wohlschlegel,
Inhibition of eukaryotic DNA replication by geminin binding to Cdt1.
2000,
Pubmed
,
Xenbase
Wohlschlegel,
Xenopus Mcm10 binds to origins of DNA replication after Mcm2-7 and stimulates origin binding of Cdc45.
2002,
Pubmed
,
Xenbase
You,
Biochemical analysis of the intrinsic Mcm4-Mcm6-mcm7 DNA helicase activity.
1999,
Pubmed
Zou,
Assembly of a complex containing Cdc45p, replication protein A, and Mcm2p at replication origins controlled by S-phase cyclin-dependent kinases and Cdc7p-Dbf4p kinase.
2000,
Pubmed
Zou,
Formation of a preinitiation complex by S-phase cyclin CDK-dependent loading of Cdc45p onto chromatin.
1998,
Pubmed
