An α-Amylase Homologue, aah3, Encodes a GPI-Anchored Membrane Protein Required for Cell Wall Integrity and Morphogenesis in Schizosaccharomyces pombe
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Glycosylphosphatidylinositol (GPI)-anchored proteins are essential for normal cellular morphogenesis and have an additional role in mediating cross-linking of glycoproteins to cell wall glucan in yeast cells. Although many GPI-anchored proteins have been characterized in <I>Saccharomyces cerevisiae</I>, none have been reported for well-characterized GPI-anchored proteins in <I>Schizosaccharomyces pombe</I> to date. Among the putative GPI-anchored proteins in <I>S. pombe</I>, four α-amylase homologs (Aah1p-Aah4p) have putative signal sequences and C-terminal GPI anchor addition signals. Disruption of <I>aah3</I><SUP>+</SUP> resulted in a morphological defect and hypersensitivity to cell wall-degrading enzymes. Biochemical analysis showed that Aah3p is an <I>N</I>-glycosylated, GPI-anchored membrane protein localized in the membrane and cell wall fractions. Conjugation and sporulation were not affected by the <I>aah3</I><SUP>+</SUP> deletion, but the ascal wall of <I>aah3</I>Δ cells was easily lysed by hydrolases. Expression of <I>aah3</I> alleles in which the conserved aspartic acid and glutamic acid residues required for hydrolase activity were replaced with alanine residues failed to rescue the morphological and ascal wall defects of <I>aah3</I>Δ cells. Taken together, these results indicate that Aah3p is a GPI-anchored protein and is required for cell and ascal wall integrity in <I>S. pombe</I>.
- Agricultural and Biological Chemistry
Agricultural and Biological Chemistry 70(6), 1454-1463, 2006-06-23
Japan Society for Bioscience, Biotechnology, and Agrochemistry