Bgs2p, a 1,3-beta-glucan synthase subunit, is essential for maturation of ascospore wall in Schizosaccharomyces pombe

Previously we have reported that Drc1p/Cps1p, a 1,3-beta-glucan synthase su bunit, is essential for division septum assembly in Schizosaccharomyces pom be. In this report, we present evidence that S. pombe Bgs2p, a 1,3-beta-glu can synthase that shows 56% identity to Drc1p/Cps1p, is essential for matur ation of ascospore wall in S. pombe but is not required for vegetative grow th. Diploid cells homozygous for the bgs2-null mutation, as well as homotha llic bgs2-null mutant haploids undergo meiosis normally. However, a 1,3-bet a-glucan containing spore wall is not assembled in these cells. The spores resulting from meiosis of a bgs2-null mutant lyse upon release from the asc us and are therefore inviable. Using a green fluorescent protein-tagged Bgs 2p, we demonstrate that Bgs2p is localized at the periphery of the ascospor e during meiosis and sporulation. However, Bgs2p is not detected in vegetat ive cells. We conclude that Bgs2p is required for 1,3-beta-glucan synthesis during ascospore wall maturation. (C) 2000 Federation of European Biochemi cal Societies. Published by Elsevier Science B.V. All rights reserved.