Structure and Composition of Walls of the Yeast Form of Verticillium albo-atrum

Abstract

Walls of the yeast form of Verticillium albo-atrum showed a granular appearance on the outer surface. The granular components could be extracted by alkali, revealing a fibrillar wall fabric. A region of circularly oriented microfibrils with a minute central ' orifice ' was commonly found at one of the cell poles and probably represented a bud scar. The material dissolved by alkali was a heteropolysaccharide-protein complex containing mannose, galactose, glucose, glucuronic acid, glucosamine and the common range of amino acids. The alkali-insoluble microfibrillar network was made of a Plinked glucan and chitin. The glucan was digested by endo-P-glucanases yielding glucose, P-I ~-1inked glucose oligomers and cellobiose, but no evidence for cellulose was found. Most of the glucan was also soluble in hot acid. The acidinsoluble glucan (hydroglucan) contained p-I ,6-links. Acid treatment produced coarse microfibrils resembling those in Saccharomyces cerevisiae walls * treated similarly. The hydroglucan was soluble in alkali leaving an insoluble microfibrillar network composed mainly of chitin. A small amount of lipid (2.7 to 3.473, mostly of the bound type, and traces of phosphate were also found.

Chemical components and their locations in the Verticillium fungicola cell wall

“…The F2Sa fraction was also an α-glucan but linked in (1→3)(1→4), with some branches in units at C-6 and (or) C-4; and finally the glucan of the residual fraction F3 was a glucopolymer, chiefly β-(1 →3) linked with lesser percentage of β-(1-4) linkages, and some branch points at C-2 position. A similar structure of an alkali-insoluble glucan was previously described by Horikoshi and Hda (1964) in the spore coats of Aspergillus oryzae, by Wang and Bartnicki-García (1970) in the walls of the yeast form of Verticillium albo-atrum, and also by Stagg and Feather (1973) in Aspergillus niger cell walls.…”

Biosynthesis of cell walls of fungi.

“…5). For more details on occurence and structure of fungal cell wall glucans, the reader is directed to more specialized articles (e.g., 15,16,205,271,277).…”

Cell-wall Composition and Structure of Yeast Cells and Conjugation Tubes of Tremella mesenterica

“…This type of P-glucan is very widespread in fungi. Many fungal walls which contain I ,3-P-1,6-P-glucans produce, upon acid hydrolysis, an insoluble ' hydroglucan ' fraction (Houwink & Kreger, 1953;Wang & Bartnicki-Garcia, 1970). There was no evidence for such an acid-insoluble P-glucan in the Tremella walls, which may indicate that the fine structure of the P-glucan from Tremella is different from that of other fungi that have been studied.…”