The Haemophilus influenzae HMW1 adhesin is glycosylated in a process that requires HMW1C and phosphoglucomutase, an enzyme involved in lipooligosaccharide biosynthesis
The Haemophilus influenzae HMW1 adhesin is glycosylated in a process that requires HMW1C and phosphoglucomutase, an enzyme involved in lipooligosaccharide biosynthesis
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DOI：
10.1046/j.1365-2958.2003.03450.x
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发表时间：
2003-05-01
影响因子：
3.6
通讯作者：
St Geme, JW
中科院分区：
文献类型：
--
作者：
Grass, S;Buscher, AZ;St Geme, JW
非分型流感嗜血杆菌是一种常见的呼吸道病原体，也是人类发病的重要原因。不可分型的流感嗜血杆菌HMW1和HMW2粘附素是介导与人上皮细胞附着的相关蛋白，这是疾病发病机制中的一个重要步骤。这些粘附素的分泌需要称为HMW1B/HMW2B和HMW1C/HMW2C的辅助蛋白。在本研究中，我们研究了HMW1C的特定功能。对突变结构的检测表明，HMW1C同时影响HMW1的大小和分泌。免疫共沉淀和酵母双杂交实验表明，HMW1C与HMW1相互作用，并在细胞质中形成复合体。更多的实验和同源性分析证实，HMW1C是HMW1糖基化所必需的，并且可能具有糖转移酶活性。多糖结构含有半乳糖、葡萄糖和甘露糖，部分似乎是由磷酸葡萄糖变位酶产生的，磷酸葡萄糖变位酶是脂寡糖生物合成的重要酶。在没有糖基化的情况下，HMW1被部分降解并有效地从生物体表面释放出来，导致粘附性降低。根据这些结果，我们得出结论，糖基化是HMW1稳定性的先决条件。此外，糖基化似乎是HMW1与细菌表面最佳连接的关键，而这又是HMW1介导的黏附所必需的，从而揭示了糖基化影响细胞-细胞相互作用的新机制。
Non-typeable Haemophilus influenzae is a common respiratory pathogen and an important cause of morbidity in humans. The non-typeable H. influenzae HMW1 and HMW2 adhesins are related proteins that mediate attachment to human epithelial cells, an essential step in the pathogenesis of disease. Secretion of these adhesins requires accessory proteins called HMW1B/HMW2B and HMW1C/HMW2C. In the present study, we investigated the specific function of HMW1C. Examination of mutant constructs demonstrated that HMW1C influences both the size and the secretion of HMW1. Co-immunoprecipitation and yeast two-hybrid assays revealed that HMW1C interacts with HMW1 and forms a complex in the cytoplasm. Additional experiments and homology analysis established that HMW1C is required for glycosylation of HMW1 and may have glycotransferase activity. The glycan structure contains galactose, glucose and mannose and appears to be generated in part by phosphoglucomutase, an enzyme important for lipooligosaccharide biosynthesis. In the absence of glycosylation, HMW1 is partially degraded and is efficiently released from the surface of the organism, resulting in reduced adherence. Based on these results, we conclude that glycosylation is a prerequisite for HMW1 stability. In addition, glycosylation appears to be essential for optimal HMW1 tethering to the bacterial surface, which in turn is required for HMW1-mediated adherence, thus revealing a novel mechanism by which glycosylation influences cell-cell interactions.