de Luna Maria das Graças, Scott-Tucker Anthony, Desvaux Mickael, Ferguson Paul, Morin Nicholas P, Dudley Edward G, Turner Sue, Nataro James P, Owen Peter, Henderson Ian R
Division of Immunity and Infection, The Medical School, University of Birmingham, Birmingham, UK.
FEMS Microbiol Lett. 2008 Jul;284(2):237-46. doi: 10.1111/j.1574-6968.2008.01207.x. Epub 2008 May 27.
Abstract Escherichia coli is a versatile organism capable of causing a variety of intestinal and extraintestinal diseases, as well as existing as part of the commensal flora. A variety of factors permit specific attachment to host receptors including fimbrial adhesins and outer membrane proteins such as autotransporters. One of the better characterized autotransporters is Antigen 43 (Ag43), the major phase-variable surface protein of E. coli. Ag43 is associated with bacterial cell-cell aggregation and biofilm formation. Nevertheless, the precise biological significance and contribution to intestinal colonization remain to be elucidated. Here we investigated the contribution of Ag43 to E. coli adherence to intestinal epithelial cells and colonization of the mouse intestine. These investigations revealed that Ag43 increased in vitro adherence of E. coli to epithelial cells by promoting bacterial cell-cell aggregation but that Ag43 did not promote specific interactions with the mammalian cells. Furthermore, Ag43 did not contribute significantly to colonization of the mouse intestine and expression of Ag43 was lost a few days after colonization of the mouse was established. Unexpectedly, considering its similarity to other adhesins, our findings suggest that Ag43 does not act as a direct colonization factor by binding to mammalian cells.
摘要 大肠杆菌是一种多能生物，能够引发多种肠道和肠道外疾病，同时也作为共生菌群的一部分而存在。多种因素使得大肠杆菌能够特异性地附着于宿主受体，包括菌毛黏附素和外膜蛋白（如自转运蛋白）。抗原43（Ag43）是特征较为明确的自转运蛋白之一，是大肠杆菌主要的相变表面蛋白。Ag43与细菌细胞间聚集及生物膜形成相关。然而，其确切的生物学意义以及对肠道定植的作用仍有待阐明。在此，我们研究了Ag43对大肠杆菌黏附于肠道上皮细胞及在小鼠肠道定植的作用。这些研究表明，Ag43通过促进细菌细胞间聚集增加了大肠杆菌在体外对上皮细胞的黏附，但Ag43并未促进与哺乳动物细胞的特异性相互作用。此外，Ag43对小鼠肠道定植的作用并不显著，且在小鼠定植建立几天后Ag43的表达就消失了。出乎意料的是，考虑到它与其他黏附素的相似性，我们的研究结果表明，Ag43并非通过与哺乳动物细胞结合而直接作为定植因子发挥作用。
