Molecular Characterization of UpaB and UpaC, Two New Autotransporter Proteins of Uropathogenic Escherichia coli CFT073
Molecular Characterization of UpaB and UpaC, Two New Autotransporter Proteins of Uropathogenic Escherichia coli CFT073
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DOI：
10.1128/iai.05322-11
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发表时间：
2012-01-01
影响因子：
3.1
通讯作者：
Schembri, Mark A.
中科院分区：
文献类型：
--
作者：
Allsopp, Luke P.;Beloin, Christophe;Schembri, Mark A.
尿路致病性大肠杆菌（UPEC）是发达国家尿路感染（UTI）的主要原因。与UPEC毒力相关的主要因素是毛粘附素，它介导对宿主受体的特异性附着并引发先天宿主反应。另一组粘连蛋白由自转运蛋白（AT）亚群代表。经基因组测序的UPEC原型菌株CFT073含有11个推测的at编码基因。在这项研究中，我们对CFT073中两个密切相关的AT粘附素：UpaB （c0426）和UpaC （c0478）进行了详细的分子表征。PCR筛选显示，upaB和upaC at编码基因在大肠杆菌中是常见的。在重组大肠杆菌K-12菌株背景下克隆并鉴定了upaB和upaC基因。这表明它们编码位于细胞表面的蛋白质，但具有不同的功能特性：UpaB介导对几种ECM蛋白的粘附，而UpaC的表达与增加的生物膜形成有关。在CFT073中，upaB被表达，而upaC被全局调控因子H-NS转录抑制。在小鼠UTI模型的竞争定殖实验中，CFT073在膀胱中的竞争明显优于其upaB（而不是upaC）等基因突变株。在单次攻毒实验中也观察到这种减弱的表型，CFT073中upaB基因的缺失显著减少了膀胱的早期定植。
Uropathogenic Escherichia coli (UPEC) is the primary cause of urinary tract infection (UTI) in the developed world. The major factors associated with virulence of UPEC are fimbrial adhesins, which mediate specific attachment to host receptors and trigger innate host responses. Another group of adhesins is represented by the autotransporter (AT) subgroup of proteins. The genome-sequenced prototype UPEC strain CFT073 contains 11 putative AT-encoding genes. In this study, we have performed a detailed molecular characterization of two closely related AT adhesins from CFT073: UpaB (c0426) and UpaC (c0478). PCR screening revealed that the upaB and upaC AT-encoding genes are common in E. coli. The upaB and upaC genes were cloned and characterized in a recombinant E. coli K-12 strain background. This revealed that they encode proteins located at the cell surface but possess different functional properties: UpaB mediates adherence to several ECM proteins, while UpaC expression is associated with increased biofilm formation. In CFT073, upaB is expressed while upaC is transcriptionally repressed by the global regulator H-NS. In competitive colonization experiments employing the mouse UTI model, CFT073 significantly outcompeted its upaB (but not upaC) isogenic mutant strain in the bladder. This attenuated phenotype was also observed in single-challenge experiments, where deletion of the upaB gene in CFT073 significantly reduced early colonization of the bladder.