Primary structure of O-linked carbohydrate chains in the cellulosome of different Clostridium thermocellum strains

The cell-free forms of the multiple cellulase-containing protein complex (cellulosome), isolated from the cellulolytic bacterium Clostridium thermocellum strains YS, ATCC 27405 and LQRI, have a total carbohydrate content of 5-7% (by mass), consisting of O-linked oligosaccharide chains. The carbohydrate chains were liberated by alkaline-borohydride treatment and fractionated as oligosaccharide alditols via gel-permeation chromatography and HPLC. The fractions were investigated by 500-MHz 1H NMR spectroscopy in combination with monosaccharide and methylation analysis and with fast-atom-bombardment mass spectrometry (FAB-MS). Cell-free and cell-associated forms of the cellulosome of C. thermocellum, as determined for strain YS, have the same oligosaccharide pattern. Based on the oligosaccharide structure, a biosynthetic pathway is suggested.