Escherichia coli K-12 possesses multiple cryptic but functional chaperone-usher fimbriae with distinct surface specificities
Escherichia coli K-12 possesses multiple cryptic but functional chaperone-usher fimbriae with distinct surface specificities
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DOI：
10.1111/j.1462-2920.2010.02202.x
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发表时间：
2010-07-01
影响因子：
5.1
通讯作者：
Beloin, Christophe
中科院分区：
文献类型：
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作者：
Korea, Charalampia-Georgia;Badouraly, Reana;Beloin, Christophe
共生和致病的大肠杆菌对宿主和环境表面的黏附是由多种粘附素介导的。尽管作为模式菌被广泛研究，但大肠杆菌K-12基因组中34%的基因具有未知的功能。我们推测其中一些可能对应于功能性粘附素。我们鉴定了E.coliK-12ycb、ybg、yfc、yad、yra、sfm和yeh操纵子，它们与伴侣/引座者途径输出的1型菌毛显示出序列和组织上的同源性。我们发现，尽管这些操纵子在实验室条件下表达很差，但其中六个在表达时仍具有功能，并促进与非生物和/或上皮细胞表面的黏附。虽然所研究的菌毛显示出不同的结合特异性，但我们获得了与其他粘附素如Ag43或1型菌毛协同/干扰的证据。我们发现，它们的表达受H-NS的负调控，除Yad外，还受到cAMP受体蛋白介导的激活和碳分解代谢的抑制。这些结果表明，ycb、yfc、yad、yra、sfm和yah操纵子编码隐蔽的但具有功能的粘附素，其在环境改变后的表达有助于E.coifs在其各种生态位中的广泛多样性的表面上黏附和定植。
Commensal and pathogenic Escherichia coli adherence to host and environmental surfaces is mediated by a variety of adhesins. Although extensively studied as a model bacterium, 34% of the genes in the E. coli K-12 genome have no known function. We hypothesized that some of them may correspond to functional adhesins. We characterized E. coli K-12 ycb, ybg, yfc, yad, yra, sfm and yeh operons, which display sequence and organizational homologies to type 1 fimbriae exported by the chaperone/usher pathway. We showed that, although these operons are poorly expressed under laboratory conditions, six of them are nevertheless functional when expressed, and promote adhesion to abiotic and/or epithelial cell surfaces. While the studied fimbriae display different binding specificities, we obtained evidence of synergy/interference with other adhesins such as Ag43 or type 1 fimbriae. We showed that their expression is under the negative control of H-NS and, except for yad, subjected to cAMP receptor protein-mediated activation and carbon catabolite repression. These results therefore demonstrate that ycb, yfc, yad, yra, sfm and yeh operons encode cryptic but functional fimbriae adhesins whose expression following environmental modifications could contribute to E. coifs ability to adhere to and colonize a wide diversity of surfaces in its various ecological niches.