The haemophilus influenzae HMW1 adhesin is a glycoprotein with an unusual N-linked carbohydrate modification
The haemophilus influenzae HMW1 adhesin is a glycoprotein with an unusual N-linked carbohydrate modification
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DOI：
10.1074/jbc.m801819200
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发表时间：
2008-09-19
影响因子：
4.8
通讯作者：
Geme, Joseph W. St., III
中科院分区：
文献类型：
--
作者：
Gross, Julia;Grass, Susan;Geme, Joseph W. St., III
流感嗜血杆菌HMW 1粘附素介导呼吸道上皮细胞的粘附，这是流感嗜血杆菌发病的关键早期步骤。流行性感冒在最近的工作中，我们证明了HMW 1经历糖基化。此外，我们观察到，HMW 1的糖基化是必不可少的HMW 1拴系到细菌表面，HMW 1介导的粘附宿主上皮细胞的先决条件。在这项研究中，我们研究了HMW 1蛋白水解片段的质谱，实现了89%的氨基酸序列覆盖率，并确定了31个新的修改网站。所有修饰位点均为天冬酰胺残基，除了一种情况外，其他均为N-连接聚糖的常规共有序列，即NX（S/T）。使用混合线性四极离子阱傅里叶变换离子回旋质谱仪的液相色谱-串联质谱分析、精确的质量测量和氘交换研究确定，修饰聚糖结构是单己糖或二己糖，而不是N-乙酰化壳二糖核心，这是N-糖基化的特征。这种不寻常的碳水化合物修饰表明，HMW 1糖基化需要一种具有新活性的糖基转移酶。
The Haemophilus influenzae HMW1 adhesin mediates adherence to respiratory epithelial cells, a critical early step in the pathogenesis of H. influenzae disease. In recent work, we demonstrated that HMW1 undergoes glycosylation. In addition, we observed that glycosylation of HMW1 is essential for HMW1 tethering to the bacterial surface, a prerequisite for HMW1-mediated adherence to host epithelium. In this study, we examined HMW1 proteolytic fragments by mass spectrometry, achieved 89% amino acid sequence coverage, and identified 31 novel modification sites. All of the modified sites were asparagine residues, in all but one case in the conventional consensus sequence of N-linked glycans, viz. NX(S/T). Liquid chromatography-tandem mass spectrometry analysis using a hybrid linear quadrupole ion trap Fourier transform ion cyclotron mass spectrometer, accurate mass measurements, and deuterium exchange studies established that the modifying glycan structures were mono- or dihexoses rather than the N-acetylated chitobiosyl core that is characteristic of N-glycosylation. This unusual carbohydrate modification suggests that HMW1 glycosylation requires a glycosyltransferase with a novel activity.