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Alpha1,4GlcNAc-capped mucin-type O-glycan inhibits cholesterol alpha-glucosyltransferase from Helicobacter pylori and suppresses H. pylori growth.
Helicobacter pylori infects over half of the world's population and is thought to be a leading cause of gastric ulcer, gastric carcinoma, and gastric malignant lymphoma of mucosa-associated lymphoid tissue type. Previously, we reported that a gland mucin (MUC6) present in the lower portion of the gastric mucosa containing alpha1,4-N-acetylglucosamine (alpha1,4GlcNAc)-capped core 2-branched O-glycans suppresses H. pylori growth by inhibiting the synthesis of alpha-glucosyl cholesterol, a major constituent of the H. pylori cell wall (Kawakubo et al. 2004. Science. 305:1003-1006). Therefore, we cloned the genomic DNA encoding cholesterol alpha-glucosyltransferase (HP0421) and expressed its soluble form in Escherichia coli. Using this soluble HP0421, we show herein that HP0421 sequentially acts on uridine diphosphoglucose and cholesterol in an ordered Bi-Bi manner. We found that competitive inhibition of HP0421 by alpha1,4GlcNAc-capped core 2-branched O-glycan is much more efficient than noncompetitive inhibition by newly synthesized alpha-glucosyl cholesterol. Utilizing synthetic oligosaccharides, alpha-glucosyl cholesterol, and monosaccharides, we found that alpha1,4GlcNAc-capped core 2-branched O-glycan most efficiently inhibits H. pylori growth. These findings together indicate that alpha1,4GlcNAc-capped O-glycans suppress H. pylori growth by inhibiting HP0421, and that alpha1,4GlcNAc-capped core 2 O-glycans may be useful to treat patients infected with H. pylori.
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