Synthesis of alpha-glucans in fission yeast spores is carried out by three alpha-glucan synthase paralogues, Mok12p, Mok13p and Mok14p

Mol Microbiol. 2006 Feb;59(3):836-53. doi: 10.1111/j.1365-2958.2005.04995.x.


Fission yeast possesses a family of (1,3)-alpha-glucan synthase-related genes; one of them, mok1+/ags1+, plays an essential function in morphogenesis during vegetative growth. Here we show that three mok1+ paralogues -mok12+, mok13+ and mok14+- are required for sporulation to succeed, acting at different stages of the spore wall maturation process. Mutation of mok12+ affected the efficiency of spore formation and spore viability. Deletion of mok13+ does not affect spore viability but the spores showed reduced resistance to stress conditions. mok14Delta mutant spores failed to accumulate the amylose-like spore wall-specific polymer. mok12+, mok13+ and mok14+ expression was restricted to sporulating cells and the proteins localized to the spore envelope but with different timing. mok11+ was also induced during the sporulation process although its deletion did not show apparently a sporulation defect. In vegetative cells, beta-glucans are more abundant than alpha-glucans (55% versus 28%). In spores, the situation was the opposite, alpha-glucans accounted for 46% while beta-glucans were approximately 38% of the total polysaccharides. We found at least two types of alpha-glucan polymers, Mok12p and Mok13p, were involved in the synthesis of the greater part of alpha-glucan in the spores envelope, a polymer that is mainly digested with alpha-1,3 glucanase, while Mok14p, homologous to starch synthases, was required for the synthesis of the iodine-reactive polymer that is made of alpha-1,4 glucose residues.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amylose / biosynthesis
  • Cell Wall / genetics
  • Cell Wall / metabolism
  • Glucans / biosynthesis*
  • Glucosyltransferases / analysis
  • Glucosyltransferases / genetics
  • Glucosyltransferases / metabolism*
  • Polymers / metabolism
  • Schizosaccharomyces / cytology
  • Schizosaccharomyces / genetics
  • Schizosaccharomyces / metabolism*
  • Sequence Deletion
  • Spores, Fungal / chemistry
  • Spores, Fungal / cytology
  • Spores, Fungal / metabolism*


  • Glucans
  • Polymers
  • Amylose
  • Glucosyltransferases
  • glucan synthase