Disruption of six unknown open reading frames from Saccharomyces cerevisiae reveals two genes involved in vacuolar morphogenesis and one gene required for sporulation.

In this report we describe the construction and basic phenotypic analysis of deletion mutants in six open reading frames (ORFs) of unknown function from the yeast Saccharomyces cerevisiae. Using the dominant kanMX marker and polymerase chain reaction (PCR) methods, deletion cassettes were constructed for five ORFs (YNL099c, YNL100w, YNL101w, YNL106c and YNL242w) located on chromosome XIV and one ORF (YOR109w) located on chromosome XV. The recovery of viable haploid deletant strains among the meiotic products of heterozygous deletants for each ORF demonstrated that none of the analysed ORFs was essential. With the exception of YNL242w, no alterations in growth characteristics or mating and sporulation efficiencies associated with deletion of the ORFs were observed. Homozygous diploid ynl242w delta cells obtained in three different genetic backgrounds were unable to sporulate, indicating that the product of this ORF is required for sporulation. Complementation of the sporulation defect by the cognate gene clone confirmed this observation. YNL106c and YOR109w are very similar and show strong sequence homology with a mammalian phosphatidylinositol-phosphate 5-phosphatase, synaptojanin, known to be involved in synaptic vesicle cycling. Strains bearing single and double deletions of YNL106c and YOR109w were seen to display abnormal vacuolar morphologies of varying degrees. Complementation tests indicated that YNL106c and YOR109w are redundant genes.