THE IDENTIFICATION OF TRANSPOSON-TAGGED MUTATIONS IN ESSENTIAL GENES THAT AFFECT CELL MORPHOLOGY IN SACCHAROMYCES-CEREVISIAE

The yeast Saccharomyces cerevisiae reproduces by budding, and many gen es are required for proper bud development. Mutations in some of these genes cause cells to die with an unusual terminal morphology-elongate d or otherwise aberrantly shaped buds. To gain insight into bud develo pment, we set out to identify novel genes that encode proteins require d for proper bud morphogenesis. Previous studies screened collections of conditional mutations to identify genes required for essential func tions, including bud formation. However, genes that are not susceptibl e to the generation of mutations that cause a conditional phenotype wi ll not be identified in such screens. To identify a more comprehensive collection of mutants, we used transposon mutagenesis to generate a l arge collection of lethal disruption mutations. This collection was us ed to identify 209 mutants with disruptions that cause an aberrant ter minal bud morphology. The disruption mutations in 33 of these mutants identify three previously uncharacterized genes as essential, and the mutant phenotypes suggest roles for their products in bud morphogenesi s.