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[摘要]：Origins of replication in higher eukaryotes appear to lack specific sequence characteristics and those mapped often appear to be spread over several kilobases. This has complicated the study of site-specific events at origins of replication in vivo. Here we show that fusion of a Gal4-binding domain to proteins of the origin of replication complex (Orc) is sufficient to direct initiation to Gal4-binding sites inserted in the Drosophila S2 cell chromosome. The activation appears to go via an authentic route, taking place only in the S phase of the cell cycle and involving the formation of a prereplication complex. We have also shown that the origin-associated acetylation of histone H4 at K12 can be directed to the region of Orc binding by the presence of Orc. We expect that this system can provide a useful tool for the study of site-specific events at origins of replication in higher eukaryotes and a means to dissect Orc-dependent and Orc-independent events at origins. |
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