PROPOSED PATHWAY FOR BIOSYNTHESIS OF THE S-LAYER GLYCOPROTEIN OF BACILLUS-ALVEI

The outer surface of the murein sacculus of the eubacterium Bacillus a lvei is covered by a surface layer (S-layer) glycoprotein. The glycan chain of this S-layer glycoprotein consists of trisaccharide repeating units with ManNAc, Gal, and Glc as constituents. From cell extracts o f B. alvei, nucleotide-activated derivatives of ManNAc, Gal, Glc, and GlcNAc were isolated. Furthermore, GDP- and dolichyl-activated oligosa ccharides were obtained. On the basis of the isolated putative glycopr otein precursors, a pathway for the biosynthesis of the oligosaccharid e chain is proposed.