Genome-wide Screen for functional polymorphisms in Saccharomyces cerevisiae influencing its growth under nonfermentable conditions

• Applicant: Dr. Stefan Wilkening
• Subject Area: General Genetics and Functional Genome Biology
• Term: from 2008 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 91732133

Identifying the genetic variation underlying quantitative trait loci (QTL) remains problematic. Conse-quently, our molecular understanding of genetically complex, quantitative traits is limited. To address this issue, we plan to comprehensively dissect a quantitative trait in Saccharomyces cerevesiae (ba-king yeast). As a quantitative trait, we have chosen the fitness of yeast to grow under nonfermentable conditions (Nfs-phenotype). In this project, the genomes of two distantly related S. cerevesiae strains will be compared: SK1 and S288c. To identify Nfs+ and Nfsalleles, we follow two approaches. First, linkage mapping of segregating QTL will be performed in strains originating from systematic crosses and backcrosses between SK1 and S288c. Linkage intervals will be mapped by whole-genome geno-typing using a high-density micro array. To identify causative polymorphisms in the identified region, single alleles of either SK1 or S288c will be deleted in a hybrid strain (SK1/S288c). In the second ap-proach, we plan to test all ~6,000 S. cerevesiae genes in parallel and in a single step. For this ap-proach, named reciprocal hemizygosity scanning (RHS), each gene is deleted individually in the SK1/S288c hybrid, and both alleles separately. The use of molecular barcodes allows the later identi-fication of single strains with differential growth behavior from a pool. Nonfermentable carbon sources have to be metabolized by respiratory pathways, which take place in the mitochondria. Because mitochondrial pathways are highly conserved between yeast and human, this project has major implications also for the discovery of regulatory mechanisms in human genes. This can lead to the identification of candidate genes for mitochondrial disorders in human.

• DFG Programme: Research Grants