Heteronuclear NMR studies of 13C-labeled yeast cell wall beta-glucan oligosaccharides.
The structures of uniformly 13C-labeled beta-glucan octa- and undeca-oligosaccharides enzymatically prepared by the yeast cell wall glucanosyl transferase of Candida albicans were characterized by using a combination of HCCH-COSY, HCCH-TOCSY, and HMBC experiments. The oligosaccharide structures indicate that the cell wall glucanosyl transferase cleaves two glucosyl units from the reducing end of the initial linear beta(1-->3) penta-oligosaccharide and subsequently transfers the remainder to another oligosaccharide at the nonreducing end via a beta(1-->6) linkage. These results indicate that the combined action of cell wall glucanase and glucanosyl transferase activities could not only introduce intrachain beta(1-->6) linkages within a single glucan strand, but also result in cross-linking of two initially separate glucan strands with concurrent introduction of intrachain beta(1-->6) linkages. Since isolated fungal membranes only synthesize linear beta(1-->3) glucan strands, wall-associated enzymes probably participate in the assembly of the final wall glucan structure during cell growth and division.
Yu
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Pharmaceutical Discovery Division, Abbott Labortories, Abbott Park, IL 60064.
Goldman
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R
Sullivan
P
P
Walker
G F
GF
Fesik
S W
SW
D002176:Candida albicans / Q000737:chemistry; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002473:Cell Wall / Q000737:chemistry; D005936:Glucans / Q000737:chemistry*; D005964:Glucosyltransferases; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009844:Oligosaccharides / Q000737:chemistry* / Q000302:isolation & purification
D005936:Glucans; D009844:Oligosaccharides; D005964:Glucosyltransferases