The CHL 1 (CTF 1) gene product of Saccharomyces cerevisiae is important for chromosome transmission and normal cell cycle progression in G2/M.
We have analyzed the CTF1 gene, identified in a screen for mutants with decreased chromosome transmission fidelity and shown to correspond to the previously identified chl1 mutation. Chl1 null mutants exhibited a 200-fold increase in the rate of chromosome III missegregation per cell division, and near wild-type rates of marker homozygosis on this chromosome by mitotic recombination. Analysis of the segregation of a marker chromosome indicated that sister chromatid loss (1:0 segregation) and sister chromatid non-disjunction (2:0 segregation) contributed equally to chromosome missegregation. A genomic clone of CHL1 was isolated and used to map its physical position on chromosome XVI. Nucleotide sequence analysis of CHL1 revealed a 2.6 kb open reading frame with a 99 kd predicted protein sequence that contained two PEST sequences and was 23% identical to the coding region of a nucleotide excision repair gene, RAD3. Domains of homology between these two predicted protein sequences included a helix-turn-helix motif and an ATP binding site containing a helicase consensus. Mutants lacking the CHL1 gene product are viable and display two striking, and perhaps interrelated, phenotypes: extreme chromosome instability and a delay in cell cycle progression in G2/M. This delay is independent of the cell cycle checkpoint that requires the function of the RAD9 gene.
Gerring
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Department of Molecular Biology and Genetics, Johns Hopkins University Medical School, Baltimore, MD 21205.
Spencer
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Hieter
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D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D002453:Cell Cycle; D002868:Chromosomal Proteins, Non-Histone; D002874:Chromosome Mapping; D015825:Chromosomes, Fungal / Q000378:metabolism*; D003001:Cloning, Molecular; D004271:DNA, Fungal / Q000737:chemistry; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D005819:Genetic Markers; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D012689:Sequence Homology, Nucleic Acid; D013172:Spores, Fungal / Q000032:analysis
C066751:CHL1 protein, S cerevisiae; D002868:Chromosomal Proteins, Non-Histone; D004271:DNA, Fungal; D005656:Fungal Proteins; D005819:Genetic Markers; D029701:Saccharomyces cerevisiae Proteins