Proteomic and microarray characterization of the AggR regulon identifies a pheU pathogenicity island in enteroaggregative Escherichia coli
Proteomic and microarray characterization of the AggR regulon identifies a pheU pathogenicity island in enteroaggregative Escherichia coli
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DOI：
10.1111/j.1365-2958.2006.05281.x
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发表时间：
2006-09-01
影响因子：
3.6
通讯作者：
Nataro, James P.
中科院分区：
文献类型：
--
作者：
Dudley, Edward G.;Thomson, Nicholas R.;Nataro, James P.
肠聚集性大肠杆菌（EAEC）通过对HEp-2细胞的聚集粘附（AA）来定义，其中细菌显示粘附于细胞表面，并且还粘附于堆叠砖状构型中的中间基质。我们以前表明，AraC同源物指定的AggR是必需的质粒编码的基因，介导AA的EAEC株042的表达。在这项研究中，我们假设AggR也控制EAEC 042中其他毒力决定因子的表达。使用蛋白质组学和微阵列分析，我们确定了第一次，AggR激活染色体基因的表达，包括25个连续的基因（aaiA-Y），这是本地化的117 kb的致病性岛（PAI）插入在pheU。这些基因中的许多在其他革兰氏阴性细菌中具有同源物，并且最近被提出构成VI型分泌系统（T6SS）。AaiC是一种分泌型蛋白，在GenBank中没有明显的同源物。携带aaiB、aaiG、aaiO或aaiP的框内缺失的EAEC菌株仍合成AaiC;然而，AaiC分泌被废除。将aai基因克隆到E. coli HB 101中的AaiA-P对AaiC的分泌是足够的。在pheU PAI内鉴定了第二个T6SS，其分泌与AaiC序列同一性无关的蛋白质。分布研究表明，aaiA和aaiC在世界各地的EAEC分离株中普遍存在，特别是在定义为典型EAEC的菌株中。这些数据支持了AggR是EAEC毒力决定因子的全局调节因子的假设，并建立在T6SS是发病机制的重要介质的假设之上。
Enteroaggregative Escherichia coli (EAEC) is defined by aggregative adherence (AA) to HEp-2 cells, where bacteria display adherence to cell surfaces and also to the intervening substratum in a stacked-brick configuration. We previously showed that an AraC homologue designated AggR is required for the expression of plasmid-encoded genes that mediate AA of EAEC strain 042. In this study, we hypothesized that AggR also controls the expression of other virulence determinants in EAEC 042. Using proteomic and microarray analysis, we identified for the first time that AggR activates the expression of chromosomal genes, including 25 contiguous genes (aaiA-Y), which are localized to a 117 kb pathogenicity island (PAI) inserted at pheU. Many of these genes have homologues in other Gram-negative bacteria and were recently proposed to constitute a type VI secretion system (T6SS). AaiC was identified as a secreted protein that has no apparent homologues within GenBank. EAEC strains carrying in-frame deletions of aaiB, aaiG, aaiO or aaiP still synthesized AaiC; however, AaiC secretion was abolished. Cloning of aai genes into E. coli HB101 suggested that aaiA-P are sufficient for AaiC secretion. A second T6SS was identified within the pheU PAI that secretes a protein unrelated by sequence identity to AaiC. Distribution studies indicated that aaiA and aaiC are commonly found in EAEC isolates worldwide, particularly in strains defined as typical EAEC. These data support the hypothesis that AggR is a global regulator of EAEC virulence determinants, and builds on the hypothesis that T6SS is an importance mediator of pathogenesis.