Structure and Biosynthesis of the Mannan Component of the Yeast Cell Envelope

Abstract

Publisher Summary The chapter focuses on the new developments concerning yeast mannan structure and biosynthesis as they relate to the organization of the cell wall and the roles played by these glycoproteins. The mechanism of mannan biosynthesis is still in a rudimentary state, partly because of the insufficient knowledge concerning mannan structure and partly because of the inherent difficulties in working with such a complex macromolecule. Detailed information of Saccharomyces cerevisiae mannan can now be sketched and facilitates the planning of experiments on, and the interpretation of results from, biosynthetic studies. Moreover, the availability of mannan mutants with known polysaccharide structural alterations should prove advantageous. Studies of mannan biosynthesis have taken three general tacks. One approach has been directed toward an elucidation of the overall process of mannan formation and translocation within the cell using “pulsechase” techniques and autoradiography. The second approach has dealt with the formation and secretion of intact mannan molecules by yeast protoplasts and the inhibition of this process by compounds that prevent protein or polysaccharide synthesis. The third approach has investigations of the enzymic processes involved in mannan synthesis, using cell-free extracts and following incorporation of radioactive mannose into endogenous and exogenous acceptors. The chapter discusses the detailed structures of specific yeast mannans.