The β4-N-acetylgalactosaminyltransferase 3 (B4GALNT3) transfers GalNAc in a β1,4-linkage to GlcNAc forming the LacdiNAc (LDN) determinant on oligosaccharides. The LacdiNAc-binding adhesin (LabA) has been suggested to mediate attachment of Helicobacter pylori to the gastric mucosa via binding to the LDN determinant. The O-glycan core chain specificity of B4GALNT3 is poorly defined. We investigated the specificity of B4GALNT3 on GlcNAc residues carried by O-glycan core 2, core 3 and extended core 1 precursors using transient transfection of CHO-K1 cells and a mucin-type immunoglobulin fusion protein as reporter protein. Binding of the LabA-positive H. pylori J99 and 26695 strains to mucin fusion proteins carrying the LDN determinant on different O-glycan core chains and human gastric mucins with and without LDN was assessed in a microtiter well-based binding assay, while the binding of ¹²⁵I-LDN–BSA to various clinical H. pylori isolates was assessed in solution. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) and western blotting confirmed the requirement of a terminal GlcNAc for B4GALNT3 activity. B4GALNT3 added a β1,4-linked GalNAc to GlcNAc irrespective of whether the latter was carried by a core 2, core 3 or extended core 1 chain. No LDN-mediated adhesion of H. pylori strains 26 695 and J99 to LDN determinants on gastric mucins or a mucin-type fusion protein carrying core 2, 3 and extended core 1 O-glycans were detected in a microtiter well-based adhesion assay and no binding of a ¹²⁵I-labelled LDN–BSA neoglycoconjugate to clinical H. pylori isolates was identified.

中文翻译：

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在不同的O-聚糖核心链上携带LacdiNAc的重组粘蛋白型蛋白无法支持幽门螺杆菌结合。

β4- N-乙酰半乳糖胺基转移酶3（B4GALNT3）将β1,4-键的GalNAc转移至GlcNAc，形成寡糖上的LacdiNAc（LDN）决定簇。已经建议，LacdiNAc结合粘附素（LabA）通过与LDN决定簇结合来介导幽门螺杆菌与胃粘膜的附着。B4GALNT3的O-聚糖核心链特异性定义不清。我们使用CHO-K1细胞和粘蛋白型免疫球蛋白融合蛋白作为报告蛋白的瞬时转染，研究了B4GALNT3对O-聚糖核心2，核心3和扩展核心1前体所携带的GlcNAc残基的特异性。LabA阳性幽门螺杆菌的结合在基于微孔的结合试验中评估了J99和26695菌株对在不同O聚糖核心链上携带LDN决定因子的粘蛋白融合蛋白菌株以及有或没有LDN的人胃粘蛋白的融合蛋白，同时¹²⁵ I-LDN–BSA与各种在溶液中评估临床幽门螺杆菌分离株。液相色谱-串联质谱（LC-MS / MS）和蛋白质印迹证实B4GALNT3活性需要末端GlcNAc。B4GALNT3向GlcNAc中添加了一个与β1,4-连接的GalNAc，无论后者是由核心2，核心3还是延伸的核心1链携带。没有LDN介导的幽门螺杆菌粘附在基于微量滴定井的粘附试验中检测到胃粘蛋白或带有核心2、3和扩展核心1 O-聚糖的粘蛋白型融合蛋白上LDN决定簇的菌株26 695和J99，并且没有结合¹²⁵ I标记的LDN鉴定了–BSA新糖结合物与临床幽门螺杆菌分离株。