title: Dosage suppressors of the dominant G1 cyclin mutant CLN3-2: identification of a yeast gene encoding a putative RNA/ssDNA binding protein.
abstract: Three G1 cyclins, CLN1, CLN2, and CLN3, have been identified in the budding yeast Saccharomyces cerevisiae. G1 cyclins are essential, albeit functionally redundant, rate-limiting activators of cell cycle initiation. We have isolated dosage-dependent suppressor genes (designated HMD genes) of the mating defect caused by CLN3-2, a dominant mutation in CLN3, HMD2 and HMD3 are identical to STE4 and STE5, respectively, HMD1 is an essential gene that encodes a protein containing a putative RNA binding domain. Overproduction of HMD1 results in a relatively specific reduction in the level of the CLN3 or CLN3-2 transcript. This reduction occurs subsequent to transcription initiation of CLN3 since overexpression of HMD1 did not affect expression of a heterologous transcript from the CLN3 promoter but did result in a reduction of CLN3 transcript expressed from a heterologous promoter. HMD1 has at least one essential role independent of its effect on CLN3 since HMD1 remains essential for viability in the absence of a functional CLN3 gene.
mesh_terms: D000595:Amino Acid Sequence; D002455:Cell Division / Q000235:genetics; D016213:Cyclins / Q000235:genetics*; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D016193:G1 Phase / Q000235:genetics; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D005799:Genes, Dominant / Q000235:genetics; D005800:Genes, Fungal; D016153:Genes, Suppressor / Q000235:genetics*; D005838:Genotype; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D012331:RNA, Fungal / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D017421:Sequence Analysis; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: C079895:CLN3 protein, S cerevisiae; D016213:Cyclins; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C090564:NAB3 protein, S cerevisiae; D009687:Nuclear Proteins; D012331:RNA, Fungal; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins