SSP2, a sporulation-specific gene necessary for outer spore wall assembly in the yeast Saccharomyces cerevisiae

Abstract

Sporulation in yeast consists of two highly coordinated processes. First, a diploid cell that is heterozygous at the mating-type locus undergoes meiosis, in which one round of DNA replication is followed by two rounds of nuclear division. Second, the meiotic products are packaged into spore cells that remain within the mother cell. A large number of genes are induced specifically during sporulation, and their products carry out different sporulation-specific events. Expression of these sporulation-specific genes is controlled by several regulators which function at different stages of the sporulation program, resulting in a cascade of gene expression following induction of meiosis. Here we describe one sporulation-specific gene, SSP2, which is induced midway through meiosis. Ssp2 shows significant homology to the predicted product of a hypothetical ORF in Candida albicans. Homozygous mutant ssp2 diploid cells fail to sporulate. In the mutant background, meiotic recombination and nuclear divisions remain normal; however, viability declines rapidly. Following meiosis, ssp2 cells form the prospore membrane, but fail to form the outer layer of the spore wall. The Ssp2 protein localizes to the spore wall after meiosis II. In addition, the ssp2 defect is also associated with delayed and reduced expression of late sporulation-specific genes. Our results suggest that SSP2 function is required after meiosis II and during spore wall formation.

The Ama1-Directed Anaphase-Promoting Complex Regulates the Smk1 Mitogen-Activated Protein Kinase During Meiosis in Yeast

“…However, in wildtype cells, the regulatory role of Cak1 in the Smk1 pathway appears to be exclusively positive since the Cak1/ Cdc28 reaction is constitutive and does not appear to be rate limiting for Cdc28 function (Kaldis et al 1998;Schindler et al 2003). ssp2 mutants complete the meiotic divisions on schedule and block in spore wall formation (Sarkar et al 2002). Our results suggest that Ssp2 functions to promote Smk1 phosphorylation.…”

“…Class III mutants: Class III consists of only two members. These mutants are in AMA1, which encodes a meiosis-specific Cdc20 family member (Cooper et al 2000), and in SSP2, which encodes a protein of unknown biochemical function that has previously been shown to be required for spore wall formation (Sarkar et al 2002). Here, we describe our analysis of AMA1.…”

The Genomes of Three Uneven Siblings: Footprints of the Lifestyles of Three Trichoderma Species

“…Secretion of Fks2p to prospore membrane requires Sps1p, while its activity is negatively regulated by Smk1p (1212,1213). In addition, three sporulationspecific proteins, Spo73p, Spo77p, and Ssp2p, also indirectly mediate ␤-glucan layer assembly with unknown functions (1214)(1215)(1216). The chitosan synthesis in spore wall requires chitin synthase Chs3p and two deacetylases Cda1p and Cda2p.…”

Janus-faced Enzymes Yeast Tgl3p and Tgl5p Catalyze Lipase and Acyltransferase Reactions

“…In addition, PC and PE synthesis are also essential for efficient sporulation, which requires rapid membrane synthesis for prospore membrane formation around each haploid nucleus (Deng et al , 2008). In yeast, among the numerous genes involved in spore formation some are specifically required for phospholipid metabolism and related signaling processes (Sarkar et al , 2002; Neiman, 2005; Li et al , 2007). …”