Basic phenotypic analysis of six novel yeast genes reveals two essential genes and one which affects the growth rate

Phenotypic analysis was performed on six mutants of Saccharomyces cerevisia e deleted in one of the following open reading frames (ORFs), located on ch romosome II: YBR254c, YBR255w, YBR257w, YBR258c, YBR259w and YBR266c. Disru ption of the ORFs was carried out in the diploid strain FY1679 using: the k anMX4 marker flanked by short sequences homologous to the target locus. Tet rad analysis following sporulation of the heterozygous disruptants showed t hat YBR254c and YBR257w are essential genes. YBR257w was later characterize d and renamed POP4, its gene product being involved in 5.8S rRNA and tRNA p rocessing (Chu ct rrl., 1997). The tetrad analysis performed for the hetero zygous disruptant for YBR266Gc showed that two of the four viable spores ga ve colonies of smaller size, reflecting a slower growth rate. Growth analys is of the disruptant haploids confirmed this defect at 30 degrees C and als o at 15 degrees C. However, complementation tests failed to confirm that th e deletion of YBR266c is responsible for this growth defect. Growth analysi s of the disruptant haploid ybr255w Delta showed a slower growth rate on YP D and minimal medium at 15 degrees C. Finally, no phenotypic effect could d r: detected associated to the disruption of ORFs YBR258c and YBR259w. Copyr ight (C) 1999 John Wiley & Sons, Ltd.