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Mapping and characterizing a new DNA replication mutant in Saccharomyces cerevisiae
Author(s) -
Eberly Susan L.,
Sakai Akira,
Sugino Akio
Publication year - 1989
Publication title -
yeast
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.923
H-Index - 102
eISSN - 1097-0061
pISSN - 0749-503X
DOI - 10.1002/yea.320050207
Subject(s) - biology , mutant , dna replication , control of chromosome duplication , eukaryotic dna replication , dna , mutation , genetics , circular bacterial chromosome , dna synthesis , microbiology and biotechnology , plasmid , chromosome , saccharomyces cerevisiae , gene
A detailed characterization of the mak 1 – 3 mutation of Saccharomyces cerevisiae has been made possible by modifying its genetic background. The mak1 – 3 mutation, which confers temperature sensitivity for growth, was originally identified as one of four mak1 mutations (Wickner and Leibowitz, 1976). Mak1 – 1 , 1 – 2 and 1 – 4 mutants are deficient in DNA topoisomerase I activity and thus have been renamed ‘ top1 ’ (Thrash et al. , 1984). Studies presented here show that the map position of MAK1 – 3 on chromosome XVI distinguishes it from TOP1 which maps on chromosome XV (Wickner and Leibowitz, 1976). An investigation of in vivo macromolecular synthesis in the mak1 – 3 mutant shows that it is deficient in DNA replication at the restrictive temperature. Experiments in which DNA synthesis was measured in synchronized cell populations indicate that the mak1 – 3 mutant is deficient in the initiation step of DNA synthesis. Furthermore, crude extracts from the mak1 – 3 mutant cells support temperature‐sensitive in vitro DNA synthesis on yeast chromosomal DNA replication origin containing plasmid pARS1, suggesting that the MAK1 gene product is directly required for in vitro DNA replication. The conclusion that mak1 – 3 is a newly identified DNA replication mutation is based on the observations that it (1) complements all DNA synthesis mutants examined, (2) maps to a previously undetected chromosomal location and (3) has a distinct terminal morphology. In light of these distinctions and of the role mak1 – 3 plays in DNA replication, it has been renamed ‘ dnal ’.