Characterization and behaviour of α‐glucan synthase in Schizosaccharomyces pombe as revealed by electron microscopy

• Published in: Yeast (Chichester, England) England), 2003-04, Vol.20 (5), p.427-438
• Main Authors: Konomi, Mami, Fujimoto, Kazushi, Toda, Takashi, Osumi, Masako
• Format: Article
• Language: English
• Subjects: Cell Wall - enzymology; Cell Wall - genetics; Cell Wall - ultrastructure; cell wall formation; Cytoskeleton - enzymology; Cytoskeleton - genetics; Cytoskeleton - ultrastructure; electron microscopy; Freeze Fracturing; freeze‐fracture replica labelling; glucan network; Glucans - genetics; Glucans - metabolism; Glucosyltransferases - chemistry; Glucosyltransferases - genetics; Glucosyltransferases - metabolism; high‐pressure freezing; immunoelectron microscopy; Microscopy, Electron, Scanning; Microscopy, Immunoelectron; Mutation; Schizosaccharomyces - enzymology; Schizosaccharomyces - genetics; Schizosaccharomyces - ultrastructure; Schizosaccharomyces pombe; Schizosaccharomyces pombe Proteins - chemistry; Schizosaccharomyces pombe Proteins - genetics; Schizosaccharomyces pombe Proteins - metabolism; α‐glucan synthase
• ISSN: 0749-503X; 1097-0061
• DOI: 10.1002/yea.974

α‐1,3‐Glucan is a cell wall component in Schizosaccharomyces pombe and is exclusive to budding yeast. We analysed the ultrastructure of the cell wall in the α‐glucan synthase mutant mok1 and determined the role of α‐1,3‐glucan in cell wall formation of Sz. pombe. The mok1 mutant cell has an abnormal shape, with swelling at the tip or at the site of the septum. The cell wall is thicker and looser than that of wild‐type cells, and the layered structure of the cell wall is broken. The glucan fibrils forming the protoplast retain a fine fibril structure, although their development into bundles is abnormal. We also report the localization of Mok1p by immunoelectron microscopy using high‐pressure freeze substitution and SDS‐digested freeze‐fracture replica labelling methods. The Mok1p is localized on the cell membrane and moves from the cell tip to the medial region during the cell cycle. These results confirm that Mok1p plays an important role in the normal construction of the cell wall and in the primary step of glucan bundle formation, and that it is required for new cell wall synthesis during vegetative growth. These findings suggest that α‐1,3‐glucan is an essential component for cell wall formation in fission yeast. Copyright © 2003 John Wiley & Sons, Ltd.