The Saccharomyces cerevisiae SPR1 gene encodes a sporulation-specific exo-1,3-beta-glucanase which contributes to ascospore thermoresistance

Abstract

A number of genes have been shown to be transcribed specifically during sporulation in Saccharomyces cerevisiae, yet their developmentalifnction is unknown. The SPRP gene is transcribed during only the late stages of sporulation. We have sequenced the SPRi gene and found that it has extensive DNA and protein sequence homology to the S. cerevisiae EXG1 gene which encodes an exo-1,3-0-glucanase expressed during vegetative growth (C. R. Vasquez de Aldana, J. Correa, P. San Segundo, A. Bueno, A. R. Nebrada, E.Mendez, and F. del Ray, Gene 97:173-182, 1991). We show that spri mutant cells do not hydrolyze p-nitrophenyl-1-D-glucoside or laminarin in a whole-cell assay for exo-1,3-13-glucanases. In addition to the absence of this enzymatic activity, sprl mutant spores exhibit reduced thermoresistance relative to isogenic wild-type spores. These observations are consistent with the notion that SPRI encodes a sporulation-specific exo-1,3-0-glucanase.In Saccharomyces cerevisiae, sporulation is initiated when a/a diploids are deprived of glucose and nitrogen. This complex pathway, which includes premeiotic DNA synthesis, high levels of genetic recombination, and two meiotic divisions, culminates in the formation of an ascus containing four haploid ascospores (reviewed in reference 11). Molecular and genetic analyses of this pathway are important because sporulation can serve as a model system for eukaryotic differentiation, i.e., for the coordination of a complex series of events that result in the formation of a new cell type. Furthermore, the process of recombination and meiosis is fundamental to eukaryotic biology.Genetic analysis has identified more than 30 complementation groups that are required for the completion of specific sporulation events (11,45); several of these genes have been cloned either by direct complementation of spo mutants, e.g., spoll (1)

Microbial Cellulose Utilization: Fundamentals and Biotechnology

“…During vegetative growth, several endo-and exo-1,3-␤-glucanases are synthesized, some of which are secreted only to remain entrapped in the cell wall whereas others are released to the surrounding medium (181). In turn, the meiotic cycle leads to the induction of a new ␤-1,3-glucanase not present in vegetatively growing cells (120,478). ␤-1,3-Glucanases possibly effect controlled cell wall hydrolysis during cell expansion, budding, conjugation, and sporulation.…”

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.…”

Senescence of the Lentinula edodes Fruiting Body After Harvesting

“…In Saccharomyces cerevisiae, three exo-β-1,3-glucanase encoding genes (EXG1, EXG2, SSG1) have been cloned and characterized (Larriba et al, 1995). The EXG1 gene encodes two main extracellular exo-β-1,3-glucanases (Kuranda and Robbins, 1987;Vázquez de Aldana et al, 1991), EXG2 encodes an exo-β-1,3-glucanase attached to the plasma membrane (Correa et al, 1992;Larriba et al, 1995) and SSG1 (also known as SPR1) encodes a sporulation-specific exo-β-1,3-glucanase (Muthukumar et al, 1993). Several other exo-β-1,3-glucanase genes have been isolated from yeasts, including Candida albicans (Chambers et al, 1993), Kluyveromyces lacis, Hansenula polymorpha and Schwanniomyces occidentalis (Esteban et al, 1999).…”