DBF8, an essential gene required for efficient chromosome segregation in Saccharomyces cerevisiae.
To investigate chromosome segregation in Saccharomyces cerevisiae, we examined a collection of temperature-sensitive mutants that arrest as large-budded cells at restrictive temperatures (L. H. Johnston and A. P. Thomas, Mol. Gen. Genet. 186:439-444, 1982). We characterized dbf8, a mutation that causes cells to arrest with a 2c DNA content and a short spindle. DBF8 maps to chromosome IX near the centromere, and it encodes a 36-kDa protein that is essential for viability at all temperatures. Mutational analysis reveals that three dbf8 alleles are nonsense mutations affecting the carboxy-terminal third of the encoded protein. Since all of these mutations confer temperature sensitivity, it appears that the carboxyl-terminal third of the protein is essential only at a restrictive temperature. In support of this conclusion, an insertion of URA3 at the same position also confers a temperature-sensitive phenotype. Although they show no evidence of DNA damage, dbf8 mutants exhibit increased rates of chromosome loss and nondisjunction even at a permissive temperature. Taken together, our data suggest that Dbf8p plays an essential role in chromosome segregation.
Houman
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Department of Cellular and Developmental Biology, Harvard University, Cambridge, Massachusetts 02138.
Holm
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D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D002875:Chromosomes / Q000502:physiology; D004271:DNA, Fungal / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D008938:Mitosis; D008969:Molecular Sequence Data; D009630:Nondisjunction, Genetic; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D013329:Structure-Activity Relationship
D018528:ATP-Binding Cassette Transporters; D004271:DNA, Fungal; D005656:Fungal Proteins; D009838:Oligodeoxyribonucleotides; C085810:STS1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins