title: CDC68, a yeast gene that affects regulation of cell proliferation and transcription, encodes a protein with a highly acidic carboxyl terminus.
abstract: The cell cycle of the budding yeast Saccharomyces cerevisiae has been investigated through the study of conditional cdc mutations that specifically affect cell cycle performance. Cells bearing the cdc68-1 mutation (J. A. Prendergast, L. E. Murray, A. Rowley, D. R. Carruthers, R. A. Singer, and G. C. Johnston, Genetics 124:81-90, 1990) are temperature sensitive for the performance of the G1 regulatory event, START. Here we describe the CDC68 gene and present evidence that the CDC68 gene product functions in transcription. CDC68 encodes a 1,035-amino-acid protein with a highly acidic and serine-rich carboxyl terminus. The abundance of transcripts from several unrelated genes is decreased in cdc68-1 mutant cells after transfer to the restrictive temperature, while at least one transcript, from the HSP82 gene, persists in an aberrant fashion. Thus, the cdc68-1 mutation has both positive and negative effects on gene expression. Our findings complement those of Malone et al. (E. A. Malone, C. D. Clark, A. Chiang, and F. Winston, Mol. Cell. Biol. 11:5710-5717, 1991), who have independently identified the CDC68 gene (as SPT16) as a transcriptional suppressor of delta-insertion mutations. Among transcripts that rapidly become depleted in cdc68-1 mutant cells are those of the G1 cyclin genes CLN1, CLN2, and CLN3/WHI1/DAF1, whose activity has been previously shown to be required for the performance of START. The decreased abundance of cyclin transcripts in cdc68-1 mutant cells, coupled with the suppression of cdc68-1-mediated START arrest by the CLN2-1 hyperactive allele of CLN2, shows that the CDC68 gene affects START through cyclin gene expression.
authors.affiliation: Department of Microbiology, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Rowley
authors.forename: R A
authors.initials: RA
authors.lastname: Singer
authors.forename: G C
authors.initials: GC
authors.lastname: Johnston
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D002453:Cell Cycle / Q000235:genetics; D018797:Cell Cycle Proteins; D016213:Cyclins / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D005838:Genotype; D006360:Heat-Shock Proteins / Q000235:genetics; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010641:Phenotype; D012331:RNA, Fungal / Q000235:genetics / Q000302:isolation & purification; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D014158:Transcription, Genetic; D035602:Transcriptional Elongation Factors
chemical_list: D018797:Cell Cycle Proteins; D016213:Cyclins; D004271:DNA, Fungal; D005656:Fungal Proteins; D006360:Heat-Shock Proteins; D012331:RNA, Fungal; C071238:SPT16 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D035602:Transcriptional Elongation Factors