SSG1, a gene encoding a sporulation-specific 1,3-beta-glucanase in Saccharomyces cerevisiae

Abstract

In Saccharomyces cerevisiae, the meiotic process is accompanied by a large increase in 1,3-13-glucandegradative activity. The molecular cloning of the gene (SSGI) encoding a sporulation-specific exo-1,3-,3-glucanase was achieved by screening a genomic library with a DNA probe obtained by polymerase chain reaction amplification using synthetic oligonucleotides designed according to the nucleotide sequence predicted from the amino-terminal region of the purified protein. The meiotic process in the yeast Saccharomyces cerevisiae, triggered upon starvation of MATa/MATct diploid strains, represents a regulated program of cellular differentiation in a relatively simple eukaryote, which includes genetic recombinations, meiotic divisions, and the encapsulation of the four haploid nuclei into progeny ascospores. As a model system for studying development, research has been directed largely toward identifying the cytological, biochemical, and genetic events that occur during sporulation and evaluating the extent to which such events are important to the process. Some of them may merely be a physiological response to changes in the conditions needed to induce sporulation and perhaps play no role at all in meiosis or spore formation. Such changes would probably occur in nonsporulating cells under the same changing conditions.

Synthesis of yeast cell wall glucan and evidence for glucan metabolism in a Saccharomyces cerevisiae whole cell system

“…One such viable mutant lacks the BGL2 gene product, initially believed to be an exoglucanase but now considered an endoglucanase (Mrsa e t al., 1993). The SSGl gene encodes a sporulation-specific (l73)-P-glucanase in S. cerevisiae (San Segundo et al, 1993). From our studies of laminaribiose release and progressive decrease in the amount of shed material over time, we may speculate that newly synthesized wall material is more prone to enzymic modification than older pre-existing glucan, which would presumably have already undergone such events.…”

Sporulation in the Budding Yeast Saccharomyces cerevisiae

“…Thus, the presence of sporulation-specific paralogs of different cell wall assembly enzymes may reflect the need to function at a more alkaline pH than the acidic milieu in which the cell wall is assembled (Ragni et al 2007a). Several other vegetative/sporulation paralogs exist, including ECM33/SPS2 (or SPS22), CRH1/CRR1, and EXG1/SPR1 (Nebreda et al 1986;Muthukumar et al 1993;San Segundo et al 1993;Terashima et al 2003;Coluccio et al 2004a;Gomez-Esquer et al 2004;Cabib et al 2008). Whether these paralogs similarly differ in their pH optima has not been reported.…”

Architecture and Biosynthesis of the Saccharomyces cerevisiae Cell Wall

“…Ssg1/Spr1 is a sporulation--specific protein. Its mRNA is expressed late in sporulation, and homozygous null diploids show a delay in the onset of ascus formation San Segundo et al 1993).…”