Spatial and temporal differences in the synthesis of(1 → 3)-β and(1 → 6)-β linkages in a wall glucan of Schizophyllum commune

Abstract

The alkali-insoluble chitin-glucan complex of the cell wall of Schizophyllum commune was briefly labeled with radioactive glucose. The glucans were solubilized after degradation of the chitin by chitinase, yielding a water-soluble fraction containing both(1 → 3)-β- and (1 → 6)-β-linked glucose residues and an alkali-soluble fraction containing only(1 → 3)-β-linked glucose residues. The mixed-linkage glucan appeared absent in the chitin-glucan complex from isolated tip wall material. A pulse-chase experiment showed that a water-soluble(1 → 3)-β-glucan is a precursor for linear(1 → 3)-β-glucan in the chitin-glucan complex but such a precursor was not found for the(1 → 6)-β-linked glucosyl residues. At the time of glucose exhaustion of the culture the ratio of(1 → 6)-β linkages to(1 → 3)-β linkages synthesized was much higher (3) than in young growing cultures (0.8).