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

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Abstract
Phenotypic analysis was performed on six mutants of Saccharomyces cerevisiae deleted in one of the following open reading frames (ORFs), located on chromosome II: YBR254c, YBR255w, YBR257w, YBR258c, YBR259w and YBR266c. Disruption of the ORFs was carried out in the diploid strain FY1679 using the kanMX4 marker flanked by short sequences homologous to the target locus. Tetrad analysis following sporulation of the heterozygous disruptants showed that YBR254c and YBR257w are essential genes. YBR257w was later characterized and renamed POP4, its gene product being involved in 5.8S rRNA and tRNA processing (Chu et al., 1997). The tetrad analysis performed for the heterozygous disruptant for YBR266c showed that two of the four viable spores gave colonies of smaller size, reflecting a slower growth rate. Growth analysis of the disruptant haploids confirmed this defect at 30°C and also at 15°C. However, complementation tests failed to confirm that the deletion of YBR266c is responsible for this growth defect. Growth analysis of the disruptant haploid ybr255wΔ showed a slower growth rate on YPD and minimal medium at 15°C. Finally, no phenotypic effect could be detected associated to the disruption of ORFs YBR258c and YBR259w. Copyright © 1999 John Wiley & Sons, Ltd.