Aggregative adherence fimbria II, a second fimbrial antigen mediating aggregative adherence in enteroaggregative Escherichia coli
Aggregative adherence fimbria II, a second fimbrial antigen mediating aggregative adherence in enteroaggregative Escherichia coli
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DOI：
10.1128/iai.65.10.4135-4145.1997
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发表时间：
1997-10-01
影响因子：
3.1
通讯作者：
Nataro, JP
中科院分区：
文献类型：
--
作者：
Czeczulin, JR;Balepur, S;Nataro, JP
肠聚集性大肠杆菌（EAEC）是发展中国家儿童腹泻的病原体。我们以前已经证明EAEC依靠质粒编码的菌毛粘附素粘附于HEp-2细胞，称为聚集粘附菌毛I（AAF/I），其基因已经被克隆和测序，然而，不是所有的EAEC株都表达AAF/I。利用TnphoA诱变技术，我们鉴定了一种新的菌毛（AAF/II），它介导人致病株042对HEp-2的粘附，AAF/II直径为5 nm，不与AAF/I抗血清结合。TnphoA鉴定了一个基因（命名为aafA），其与AAF/I的菌毛亚基aggA具有显著的同源性（在氨基酸水平上25%的同一性和47%的相似性）。当通过多组氨酸标签进行超表达和纯化时，AafA蛋白组装成5-nm直径的细丝，其结合抗AAF/II抗血清，克隆的aafA基因补充了aggA基因中的突变，以赋予AAF/I基因簇的菌毛表达弗拉姆，表现出AAF/II而不是AAF/I的表型特征，aafA突变体在培养物中不粘附于人肠组织，表明AAF/II在肠定殖中的作用。通过使用来自菌毛生物合成基因的AAF/I和AAF/II的DNA探针，我们表明AAF/I和AAF/II各自仅在少数EAEC菌株中发现，我们的数据表明AAF粘附素代表了一个新的菌毛粘附素家族，其介导了EAEC的聚集粘附。
Enteroaggregative Escherichia coli (EAEC) has been implicated as an agent of pediatric diarrhea in the developing world. We have shown previously that EAEC adheres to HEp-2 cells by virtue of a plasmid-encoded fimbrial adhesin designated aggregative adherence fimbria I (AAF/I), the genes for which have been cloned and sequenced, However, not all EAEC strains express AAF/I. Using TnphoA mutagenesis, me have characterized a novel fimbria (designated AAF/II) which mediates HEp-2 adherence of the human-pathogenic strain 042, AAF/II is 5 nm in diameter and does not bind AAF/I antiserum, as determined by immunogold transmission electron microscopy. TnphoA identified a gene (designated aafA) which bears significant homology to aggA, the fimbrial subunit of AAF/I (25% identity and 47% similarity at the amino acid level), When hyperexpressed and purified by polyhistidine tagging, the AafA protein assembled into 5-nm-diameter filaments which bound anti-AAF/II antiserum, The cloned aafA gene complemented a mutation in the aggA gene to confer fimbrial expression fram the AAF/I gene cluster, manifesting phenotypes characteristic of AAF/II but not AAF/I, The aafA mutant did not adhere to human intestinal tissue in culture, suggesting a role for AAF/II in intestinal colonization, By using DNA probes for AAF/I and AAF/II derived from fimbrial biosynthesis genes, we show that AAF/I and AAF/II are each found in only a minority of EAEC strains, suggesting that still more EAEC adhesins exist, Our data suggest that AAF adhesins represent a new family of fimbrial adhesins which mediate aggregative adherence in EAEC.