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Showing 1 to 15 of 15 for “"helicase loading"”.
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Single-molecule studies of eukaryotic helicase loading
… in eukaryotic DNA replication initiation is the loading of the heterohexameric Mcm2-7 helicase. In eukaryotes helicase loading is tightly regulated to ensure that this event only occurs during the GI phase of the cell cycle. Because helicase activation can only occur once cells enter S phase, …
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An ORC Flip Enables Bidirectional Helicase Loading
… is the licensing of all potential origins by loading two inactive Mcm2-7 replicative DNA helicases around the origin DNA in a head-to-head double hexamer. This conformation prepares the helicases to initiate bidirectional replication upon entry into S-phase. Interactions between three proteins …
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The role of Orc6 in ORC binding-site switching during helicase loading
… the origin recognition complex (ORC) coordinates loading of two Mcm2-7 hexameric helicases in opposite orientations to form the Mcm2-7 double hexamer. These Mcm2-7 double hexamers mark sites of eventual bidirectional replication initiation upon entering S-phase, when activation of these helicases …
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The role of DNA sequence during helicase loading at S. cerevisiae origins of replication
… phase of the cell cycle, the Mcm2-7 replicative helicase is loaded at all potential origins of replication but remains inactive until S phase. Although the proteins involved in helicase loading have been elucidated, little is understood about the role of origin DNA sequence in helicase loading …
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Multiple roles of the replication initiation protein Cdtl during helicase loading in S. cerevisiae
… this coordination is the tightly regulated loading and activation of the eukaryotic replicative DNA helicase, the hetero-hexameric Mcm2-7 complex. As cells enter G1 phase of the cell cycle, all potential sites of replication initiation are selected by the loading of inactive Mcm2-7 double …
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Keep the ORCs at bay : how eukaryotic cells ensure one round of DNA replication per cell cycle
… separation of two key replication events: helicase loading and helicase activation. Helicase loading occurs during the G1 phase of the cell cycle. In S. cerevisiae cells, Cyclin-Dependent Kinases (CDKs) prevent helicase loading outside of G1 by phosphorylating three of the four …
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Biochemical and Biophysical Characterization of Replicative Helicase Loading by <i>Vibrio cholerae</i> DciA, Crystal Structure of a Monoclonal Antibody Bound to a C-Terminal Fragment of EBNA-1 from Epstein Barr Virus
… origins of replication to begin the process of loading replicative helicases onto the genome. The loading of the helicase requires the action of an accessory protein, named a “loader”. Studies on well-characterized loaders have outlined how the bacterial DnaB replicative helicase is loaded via …
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Changing protein-DNA interactions promote ORC binding site exchange during replication origin licensing
… of this process is the eukaryotic replicative helicase, Mcm2-7, which leads the replication process by unwinding the DNA strands at the front of the replication machinery. To prepare for bidirectional replication, the hexameric Mcm2-7 helicases must be loaded onto origins of replication as …
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Mechanisms preventing DNA replication between Meiosis I and Meiosis II
… two distinct steps of DNA replication: (1) loading of the replicative helicase onto replication origins, and (2) activation of the replicative helicase. CDK and the meiosis-specific kinase Ime2 cooperatively inhibit helicase loading during the meiotic divisions, and their simultaneous …
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The Roles of the Mcm2-7 Tails in Replication Initiation
… begins when two copies of the replicative helicase, the Mcm2-7 complex, are loaded onto DNA. However, these helicases are loaded in an inactive state, and are not activated until the following S phase. As cells enter S phase, the action of two kinases, DDK and S-CDK, facilitates the …
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Investigation of Cdc45 function during helicase activation
Eukaryotic DNA replication requires the stepwise loading of Mcm2-7 helicase complexes at origins of replication. These loaded helicases need to be activated during DNA replication initiation to unwind the DNA double helix and provide a ssDNA template for replicative DNA polymerases. Eukaryotic …
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Single-molecule studies of the mechanism of eukaryotic helicase activation
… two key events that center the replicative DNA helicase Mcm2-7: helicase loading and helicase activation. During G1 phase, two inactive Mcm2-7 are loaded unto origin DNA. Upon entry into S phase, the association of multiple factors will promote helicase activity. Although loaded helicases mark …
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Regulation of DNA replication by PP2A family phosphatases
… dual role in this regulation both by restricting helicase loading (licensing) to G1 phase, and by activating origin firing in S phase. The essential S-CDK phosphorylation of the limiting initiation proteins, Sld2 and Sld3, is sufficient for CDK’s role in replisome activation in Saccharomyces …
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Impact of DNA accessibility and sequence on eukaryotic origin licensing
… origin licensing, two hexamers of the eukaryotic helicase, Mcm2-7, are loaded at potential origins of replication in a head-to-head orientation. They remain together, inactive, until entry into S phase. Origin licensing depends on three proteins, the origin-recognition complex (ORC), Cdc6, and …
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Functional dissection of the S. cerevisiae helicase activating factor Cdc45
… initiation requires two essential steps: helicase loading and activation. During the G1 to S transition, loaded Mcm2-7 helicases are activated by the S-CDK (S phase cyclin-dependent kinase)- and DDK (Dbf4-dependent kinase)- dependent recruitment of the helicase activating proteins Cdc4S …