Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
???displayArticle.abstract???
During late mitosis and early G1, a series of proteins are assembled onto replication origins that results in them becoming 'licensed' for replication in the subsequent S phase. In Xenopus this first involves the assembly onto chromatin of the Xenopus origin recognition complex XORC, and then XCdc6, and finally the RLF-M component of the replication licensing system. In this paper we examine changes in the way that XORC associates with chromatin in the Xenopus cell-free system as origins become licensed. Restricting the quantity of XORC on chromatin reduced the extent of replication as expected if a single molecule of XORC is sufficient to specify a single replication origin. During metaphase, XOrc1 associated only weakly with chromatin. In early interphase, XOrc1 formed a strong complex with chromatin, as evidenced by its resistance to elution by 200 mM salt, and this state persisted when XCdc6 was assembled onto the chromatin. As a consequence of origins becoming licensed the association of XOrc1 and XCdc6 with chromatin was destabilised, and XOrc1 became susceptible to removal from chromatin by exposure to either high salt or high Cdk levels. At this stage the essential function for XORC and XCdc6 in DNA replication had already been fulfilled. Since high Cdk levels are required for the initiation of DNA replication, this 'licensing-dependent origin inactivation' may contribute to mechanisms that prevent re-licensing of replication origins once S phase has started.
Bell,
ATP-dependent recognition of eukaryotic origins of DNA replication by a multiprotein complex.
1992, Pubmed
Bell,
ATP-dependent recognition of eukaryotic origins of DNA replication by a multiprotein complex.
1992,
Pubmed
Blow,
Initiation of DNA replication in nuclei and purified DNA by a cell-free extract of Xenopus eggs.
1986,
Pubmed
,
Xenbase
Blow,
A role for the nuclear envelope in controlling DNA replication within the cell cycle.
1988,
Pubmed
,
Xenbase
Blow,
Preventing re-replication of DNA in a single cell cycle: evidence for a replication licensing factor.
1993,
Pubmed
,
Xenbase
Blow,
A cdc2-like protein is involved in the initiation of DNA replication in Xenopus egg extracts.
1990,
Pubmed
,
Xenbase
Broek,
Involvement of p34cdc2 in establishing the dependency of S phase on mitosis.
1991,
Pubmed
Burkhart,
Interactions of human nuclear proteins P1Mcm3 and P1Cdc46.
1995,
Pubmed
Chong,
Purification of an MCM-containing complex as a component of the DNA replication licensing system.
1995,
Pubmed
,
Xenbase
Chong,
Characterization of the Xenopus replication licensing system.
1997,
Pubmed
,
Xenbase
Coleman,
The Xenopus Cdc6 protein is essential for the initiation of a single round of DNA replication in cell-free extracts.
1996,
Pubmed
,
Xenbase
Diffley,
Two steps in the assembly of complexes at yeast replication origins in vivo.
1994,
Pubmed
,
Xenbase
Diffley,
Once and only once upon a time: specifying and regulating origins of DNA replication in eukaryotic cells.
1996,
Pubmed
Diffley,
Protein-DNA interactions at a yeast replication origin.
1992,
Pubmed
Donovan,
Cdc6p-dependent loading of Mcm proteins onto pre-replicative chromatin in budding yeast.
1997,
Pubmed
,
Xenbase
Fang,
Evidence that the G1-S and G2-M transitions are controlled by different cdc2 proteins in higher eukaryotes.
1991,
Pubmed
,
Xenbase
Grallert,
The ORC1 homolog orp1 in fission yeast plays a key role in regulating onset of S phase.
1996,
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
Hua,
A role for Cdk2 kinase in negatively regulating DNA replication during S phase of the cell cycle.
1997,
Pubmed
,
Xenbase
Hyrien,
Chromosomal replication initiates and terminates at random sequences but at regular intervals in the ribosomal DNA of Xenopus early embryos.
1993,
Pubmed
,
Xenbase
Jackson,
Early events in DNA replication require cyclin E and are blocked by p21CIP1.
1995,
Pubmed
,
Xenbase
Kubota,
Identification of the yeast MCM3-related protein as a component of Xenopus DNA replication licensing factor.
1995,
Pubmed
,
Xenbase
Kubota,
Licensing of DNA replication by a multi-protein complex of MCM/P1 proteins in Xenopus eggs.
1997,
Pubmed
,
Xenbase
Kubota,
Determination of initiation of DNA replication before and after nuclear formation in Xenopus egg cell free extracts.
1993,
Pubmed
,
Xenbase
Lei,
Physical interactions among Mcm proteins and effects of Mcm dosage on DNA replication in Saccharomyces cerevisiae.
1996,
Pubmed
Liang,
Persistent initiation of DNA replication and chromatin-bound MCM proteins during the cell cycle in cdc6 mutants.
1997,
Pubmed
Madine,
MCM3 complex required for cell cycle regulation of DNA replication in vertebrate cells.
1995,
Pubmed
,
Xenbase
Mahbubani,
Cell cycle regulation of the replication licensing system: involvement of a Cdk-dependent inhibitor.
1997,
Pubmed
,
Xenbase
Mahbubani,
DNA replication initiates at multiple sites on plasmid DNA in Xenopus egg extracts.
1992,
Pubmed
,
Xenbase
Mimura,
Xenopus Cdc45-dependent loading of DNA polymerase alpha onto chromatin under the control of S-phase Cdk.
1998,
Pubmed
,
Xenbase
Nishitani,
p65cdc18 plays a major role controlling the initiation of DNA replication in fission yeast.
1995,
Pubmed
Piatti,
Activation of S-phase-promoting CDKs in late G1 defines a "point of no return" after which Cdc6 synthesis cannot promote DNA replication in yeast.
1996,
Pubmed
Romanowski,
The Xenopus origin recognition complex is essential for DNA replication and MCM binding to chromatin.
1996,
Pubmed
,
Xenbase
Rowles,
Interaction between the origin recognition complex and the replication licensing system in Xenopus.
1996,
Pubmed
,
Xenbase
Saha,
Human CDC6/Cdc18 associates with Orc1 and cyclin-cdk and is selectively eliminated from the nucleus at the onset of S phase.
1998,
Pubmed
Strausfeld,
Cip1 blocks the initiation of DNA replication in Xenopus extracts by inhibition of cyclin-dependent kinases.
1994,
Pubmed
,
Xenbase
Strausfeld,
Both cyclin A and cyclin E have S-phase promoting (SPF) activity in Xenopus egg extracts.
1996,
Pubmed
,
Xenbase
Tada,
The RLF-B component of the replication licensing system is distinct from Cdc6 and functions after Cdc6 binds to chromatin.
1999,
Pubmed
,
Xenbase
Tada,
The replication licensing system.
1998,
Pubmed
,
Xenbase
Thömmes,
The RLF-M component of the replication licensing system forms complexes containing all six MCM/P1 polypeptides.
1997,
Pubmed
,
Xenbase
Zou,
Formation of a preinitiation complex by S-phase cyclin CDK-dependent loading of Cdc45p onto chromatin.
1998,
Pubmed