Analysis of the autonomous replication behavior in human cells of the dihydrofolate reductase putative chromosomal origin of replication.

AUTOR(ES)

Caddle, M S

RESUMO

Chinese hamster genomic DNA sequences from the region downstream of the dihydrofolate reductase (DHFR) gene reported to contain a chromosomal origin of bidirectional DNA replication (OBR-1) were tested for their ability to support autonomous DNA replication in human cells. A 13.3 kilobase fragment containing OBR-1 and surrounding sequences supported replication in short-term and long-term replication assays, while a 4.5 kb fragment containing OBR-1 did not support substantial replication in either assay. These results are consistent with our previous observations that large fragments of human DNA support replication, while smaller fragments are less efficient. The replication activities of plasmids containing OBR-1 were no greater than those of randomly chosen human fragments of similar size. Furthermore, two-dimensional gel analysis of plasmids containing OBR-1 indicated that initiation does not preferentially occur within the OBR-1 region. These results suggest that in the context of autonomous replication, the DHFR sequences tested do not contain genetic information specifying site-specific replication initiation. Possible implications of these results for chromosomal replication are discussed.

Documentos Relacionados

• RIP60, a mammalian origin-binding protein, enhances DNA bending near the dihydrofolate reductase origin of replication.
• Autonomous replication of human chromosomal DNA fragments in human cells.
• Autonomous replication of a DNA fragment containing the chromosomal replication origin of the human c-myc gene.
• Purified dnaA protein in initiation of replication at the Escherichia coli chromosomal origin of replication.
• Human mitochondrial DNA: analysis of 7S DNA from the origin of replication.