Solution structure of the novel dispersin protein of enteroaggregative Escherichia coli.
Solution structure of the novel dispersin protein of enteroaggregative Escherichia coli.
复制标题
新型肠道聚集性大肠杆菌分散素蛋白的溶液结构。
DOI：
10.1111/j.1365-2958.2007.05985.x
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发表时间：
2007
影响因子：
3.6
通讯作者：
Nataro,JamesP
中科院分区：
文献类型：
--
作者：
Velarde,JorgeJ;Varney,KristenM;Inman,KeithG;Farfan,Mauricio;Dudley,Edward;Fletcher,Jonathan;Weber,DavidJ;Nataro,JamesP
肠聚集性大肠杆菌（EAEC）越来越被认为是婴儿和旅行者腹泻的重要原因，它表现出与上皮细胞粘附的聚集性、叠砖状模式。粘附是由聚集体粘附菌毛（AAFs）介导的，其编码在pAA毒力质粒上。我们最近描述了一种高度流行的pAA质粒携带基因aap，它编码一种分泌到细菌细胞表面的蛋白质（昵称为分散素）。分散素缺失突变体显示出一种独特的超聚集表型，伴随着AAF菌毛在细菌细胞表面的塌陷。为了研究这种效应的机制，我们利用溶液核磁共振分析了EAEC菌株042的分散蛋白结构，发现在23个分散蛋白等位基因中存在一个稳定的β -三明治，表面净正电荷为+3 ~ +4。实验数据表明，分散蛋白与细菌表面的脂多糖非共价结合。我们还发现AAF细胞器向细菌表面提供正电荷，这表明分散素在毛层功能中的作用是克服AAF与细菌表面之间的静电吸引力。
EnteroaggregativeEscherichia coli(EAEC), increasingly recognized as an important cause of infant and travelers' diarrhoea, exhibits an aggregative, stacked‐brick pattern of adherence to epithelial cells. Adherence is mediated by aggregative adherence fimbriae (AAFs), which are encoded on the pAA virulence plasmid. We recently described a highly prevalent pAA plasmid‐borne gene,aap, which encodes a protein (nicknamed dispersin) that is secreted to the bacterial cell surface. Dispersin‐null mutants display a unique hyper‐aggregating phenotype, accompanied by collapse of AAF pili onto the bacterial cell surface. To study the mechanism of this effect, we solved the structure of dispersin from EAEC strain 042 using solution NMR, revealing a stable beta‐sandwich with a conserved net positive surface charge of +3 to +4 among 23 dispersin alleles. Experimental data suggest that dispersin binds non‐covalently to lipopolysaccharide on the surface of the bacterium. We also show that the AAF organelles contribute positive charge to the bacterial surface, suggesting that dispersin's role in fimbrial function is to overcome electrostatic attraction between AAF and the bacterial surface.