The SPS100 gene of Saccharomyces cerevisiae is activated late in the sporulation process and contributes to spore wall maturation.
We previously described the use of a differential hybridization screen of a genomic DNA library of Saccharomyces cerevisiae to identify sporulation-specific (SPS) genes (A. Percival-Smith and J. Segall, Mol. Cell. Biol. 4:142-150, 1984). This initial screen identified 14 SPS genes that are first expressed 6 to 8 h after transfer of cells to sporulation medium. Accumulation of transcripts corresponding to these genes becomes maximal at 8 to 12 h of sporulation, the time at which meiotic events are nearing completion, and by 15 h of sporulation, transcript levels are beginning to decrease. In the present study two additional SPS genes, first expressed at 12 h of sporulation, were isolated. The steady-state level of transcripts corresponding to these two genes, termed SPS100 and SPS101, remains unchanged from 15 to 35 h, a time coincident with spore wall maturation. The nature of the putative 34.2-kilodalton protein encoded by the SPS100 gene is consistent with its being a component of the glycoprotein matrix of the spore wall; the protein contains a potential signal sequence and cleavage site and numerous sites for potential glycosylation. A MATa sps100/MAT alpha sps100 strain was found to be indistinguishable from the wild-type strain when assessed for efficiency of ascus formation and spore viability. However, a more detailed analysis of the mutant strain revealed that the SPS100 gene product serves a protective role during the early stages of spore wall formation. The time at which resistance to ether could first be detected in developing spores was delayed by 5 h in the mutant strain relative to the wild-type strain. This phenotype is presumably a reflection of a defect in spore wall maturation. This study has confirmed that temporally distinct classes of sporulation-specific genes are sequentially activated during the process of meiosis and spore formation and has shown that the SPS100 gene, identified on the basis of its developmental-specific expression pattern, contributes to spore development.
Law
D T
DT
Department of Biochemistry, University of Toronto, Ontario, Canada.
Segall
J
J
D000595:Amino Acid Sequence; D001483:Base Sequence; D002473:Cell Wall / Q000502:physiology; D002872:Chromosome Deletion; D004271:DNA, Fungal / Q000235:genetics; D005786:Gene Expression Regulation; D005796:Genes; D005822:Genetic Vectors; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000502:physiology; D013172:Spores, Fungal / Q000502:physiology; D014158:Transcription, Genetic
D004271:DNA, Fungal