Involvement of lipoprotein NlpI in the virulence of adherent invasive Escherichia coli strain LF82 isolated from a patient with Crohn's disease
Involvement of lipoprotein NlpI in the virulence of adherent invasive Escherichia coli strain LF82 isolated from a patient with Crohn's disease
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DOI：
10.1128/iai.72.5.2484-2493.2004
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发表时间：
2004-05-01
影响因子：
3.1
通讯作者：
Darfeuille-Michaud, A
中科院分区：
文献类型：
--
作者：
Barnich, N;Bringer, MA;Darfeuille-Michaud, A
从克罗恩病（CD）患者的慢性病变中回收的大肠杆菌菌株LF 82能够粘附并侵入培养的肠上皮细胞，并在巨噬细胞内复制。一个突变体选择其受损的能力，侵入上皮细胞有一个插入的Tn phoA转座子内nlpI基因编码的脂蛋白NIPI。一个NIPI阴性的同基因突变体显示其粘附能力降低了35倍，侵入肠-407细胞的能力降低了45倍，但其在巨噬细胞内存活和复制的能力与野生型菌株LF 82相似。此外，该突变体不表达鞭毛并合成非常少量的1型皮利。在NIPI阴性突变体中1型皮利的下调是由于位于fim操纵子上游的可逆DNA元件的OFF位置的优先开关所致。FimB和FimE重组酶协同作用以控制开关，并且观察到fimB和fimE mRNA水平的大幅降低。鞭毛结构的缺失与fliC mRNA水平急剧下降19倍相关，而与FlhD、C、转录调节因子和sigma（28）转录因子无关。NIPI在毒力中的关键作用独立于1型皮利和运动性，因为诱导的1型菌毛表达和/或细菌与肠上皮细胞之间的强制接触不能恢复NIPI突变体粘附和侵入肠上皮细胞的能力。
Escherichia coli strain LF82 recovered from a chronic lesion of a patient with Crohn's disease (CD) is able to adhere to and invade cultured intestinal epithelial cells and to replicate within macrophages. One mutant selected for its impaired ability to invade epithelial cells had an insertion of a Tn phoA transposon within the nlpI gene encoding the lipoprotein NIpI. A NIpI-negative isogenic mutant showed a 35-fold decrease in its ability to adhere to and a 45-fold decrease in its ability to invade Intestine-407 cells, but its ability to survive and to replicate within macrophages was similar to that of wild-type strain LF82. In addition, this mutant did not express flagella and synthesized very small amounts of type 1 pili. Downregulation of type 1 pili in the NIpI-negative mutant resulted from a preferential switch toward the OFF position of the invertible DNA element located upstream of the fim operon. The FimB and FimE recombinases act in concert to control the switch, and a large decrease in fimB and fimE mRNA levels was observed. The absence of flagellar structures correlated with a drastic 19-fold decrease in the fliC mRNA level, regardless of the FlhD,C, transcriptional regulator and of the sigma(28) transcription factor. The key role of NIpI in virulence is independent of type 1 pili and motility, since induced type 1 pilus expression and/or forced contact between bacteria and intestinal epithelial cells did not restore the ability of the NIpI mutant to adhere to and to invade intestinal epithelial cells.