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Mol. Cell. Biol., 02 1997, 553-563, Vol 17, No. 2
L Zou, J Mitchell and B Stillman
The CDC45 gene of Saccharomyces cerevisiae was isolated by complementation
of the cold-sensitive cdc45-1 mutant and shown to be essential for cell
viability. Although CDC45 genetically interacts with a group of MCM genes
(CDC46, CDC47, and CDC54), the predicted sequence of its protein product
reveals no significant sequence similarity to any known Mcm family member.
Further genetic characterization of the cdc45-1 mutant demonstrated that it
is synthetically lethal with orc2- 1, mcm2-1, and mcm3-1. These results not
only reveal a functional connection between the origin recognition complex
(ORC) and Cdc45p but also extend the CDC45-MCM genetic interaction to all
known MCM family members that were shown to be involved in replication
initiation. Initiation of DNA replication in cdc45-1 cells was defective,
causing a delayed entry into S phase at the nonpermissive temperature, as
well as a high plasmid loss rate which could be suppressed by tandem copies
of replication origins. Furthermore, two-dimensional gels directly showed
that chromosomal origins fired less frequently in cdc45-1 cells at the
nonpermissive temperature. These findings suggest that Cdc45p, ORC, and Mcm
proteins act in concert for replication initiation throughout the genome.
Copyright © 1997, American Society for Microbiology
CDC45, a novel yeast gene that functions with the origin recognition complex and Mcm proteins in initiation of DNA replication
Cold Spring Harbor Laboratory, New York 11724, USA.
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