Studies on Glucosyltransferase and Endogenous Glucosyl Acceptor in Bacillus cereus AHU 1030 Membranes

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Abstract
A glucosyltransferase, extracted from the membranes of Bacillus cereus AH{U 1030 with Tris-HCl buffer containing 0.1 % Triton X-100 at pH 9.5, was separated from an endogenous glucosyl acceptor by chromatography on DEAE-Sepharose CL-6B subsequent to chromatography on Sepharose 6B. Structural analysis data showed that the glucosyl acceptor was a glycerol phosphate polymer linked to β-gentiobiosyl diglyceride. The enzyme catalyzed the transfer of glucosyl residues from UDP-glucose to C-2 of the glycerol residues of repeating units of the acceptor. On the other hand, a lipoteichoic acid which contained 0.3 D-alanme residue per phosphorus was isolated from the cells by phenol treatment at pH 4.6. Except for the presence of D-alanine, this lipoteichoic acid had the same structure as the glucosyl acceptor. The rate of glucosylation observed with the D-alanine-containing lipo teichoic acid as the substrate was less than 40% of that observed with the D-alaninefree lipoteichoic acid, indicating that the ester-linked D-alanine in the lipoteichoic acid interferes with the action of the glucosyltransferase. The enzyme also catalyzed glucosylation of poly(glycerol phosphate) which was synthesized in the reaction of a separate enzyme fraction with CDP-glycerol. Thus, it is likely that the glucosyl transferase functions in the synthesis of cell wall teichoic acid.