Large-scale phenotypic analysis--the pilot project on yeast chromosome III.

In 1993, a pilot project for the functional analysis of newly discovered open reading frames, presumably coding for proteins, from yeast chromosome III was launched by the European Community. In the frame of this programme, we have developed a large-scale screening for the identification of gene/protein functions via systematic phenotypic analysis. To this end, some 80 haploid mutant yeast strains were constructed, each carrying a targeted deletion of a single gene obtained by HIS3 or TRP1 transplacement in the W303 background and a panel of some 100 growth conditions was established, ranging from growth substrates, stress to, predominantly, specific inhibitors and drugs acting on various cellular processes.

A novel nuclear gene, CBT1, essential for mitochondrial cytochrome b formation: terminal processing of mRNA and intron dependence.

We describe a new nuclear gene, CBT1 (Cytochrome B Termination), specifically involved in the generation of mature mRNA of cytochrome b in yeast mitochondria. Disruption of CBT1 (corresponding to ORF YKL 208W) results in a respiratory deficiency (no growth on acetate and ethanol, a reduced growth on glycerol, and a moderate growth on lactate). Cytochrome b is practically undetectable spectrally, while cytochromes a and a3 (cytochrome oxidase) appear unaffected by the disruption.

Sterol esterification in yeast: a two-gene process.

Unesterified sterol modulates the function of eukaryotic membranes. In human cells, sterol is esterified to a storage form by acyl-coenzyme A (CoA): cholesterol acyl transferase (ACAT). Here, two genes are identified, ARE1 and ARE2, that encode ACAT-related enzymes in yeast.

Sequence and analysis of 24 kb on chromosome II of Saccharomyces cerevisiae.

In the course of the European yeast genome sequencing project, we determined 23,920 bp of a continuous chromosome II right arm sequence. Analysis of data revealed 13 open reading frames (ORFs), three of which corresponded to previously identified genes; two tRNA genes and one repetitive element. One ORF showed considerable homology (46%) to a hypothetical chromosome III gene; another, putatively very hydrophobic gene product, was 30% identical to the heat-shock protein HSP30.

Complete DNA sequence of yeast chromosome II.

In the framework of the EU genome-sequencing programmes, the complete DNA sequence of the yeast Saccharomyces cerevisiae chromosome II (807 188 bp) has been determined. At present, this is the largest eukaryotic chromosome entirely sequenced. A total of 410 open reading frames (ORFs) were identified, covering 72% of the sequence.