Functional analysis of the Tsh autotransporter from an avian pathogenic Escherichia coli strain
Functional analysis of the Tsh autotransporter from an avian pathogenic Escherichia coli strain
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DOI：
10.1128/iai.72.10.5548-5554.2004
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发表时间：
2004-10-01
影响因子：
3.1
通讯作者：
Stathopoulos, C
中科院分区：
文献类型：
--
作者：
Kostakioti, M;Stathopoulos, C
温度敏感血凝素 (Tsh) 是一种由禽致病性大肠杆菌菌株分泌的自转运蛋白，该菌株定植于呼吸道并导致气囊炎、心包炎和大肠杆菌败血病。它被合成为 140 kDa 前体蛋白，其加工产生 106 kDa 过客结构域 (Tsh(s)) 和 33 kDa β 结构域 (Tsh(beta))。 Tsh(s) 内存在保守的 7 个氨基酸丝氨酸蛋白酶基序，将该蛋白归类为自转运蛋白亚家族，称为肠杆菌科丝氨酸蛋白酶自转运蛋白。在这项研究中，我们报告纯化的 Tsh 能够粘附红细胞、血红蛋白以及细胞外基质蛋白纤连蛋白和 IV 型胶原蛋白。我们还证明 Tsh(s) 对酪蛋白具有蛋白水解活性，并且我们提供的实验证据证明丝氨酸 259 对于蛋白酶功能至关重要。然而，该残基不是粘附底物所必需的，并且用丙氨酸替代它并不会消除结合活性。总之，我们的结果表明 Tsh 是一种双功能蛋白，具有粘附和蛋白水解特性。
The temperature-sensitive hemagglutinin (Tsh) is an autotransporter protein secreted by avian-pathogenic Escherichia coli strains that colonize the respiratory tract and lead to airsacculitis, pericarditis, and colisepticemia. It is synthesized as a 140-kDa precursor protein, whose processing results in a 106-kDa passenger domain (Tsh(s)) and a 33-kDa beta-domain (Tsh(beta)). The presence of a conserved 7-amino-acid serine protease motif within Tsh(s) classifies the protein in a subfamily of autotransporters, known as serine protease autotransporters of the Enterobacteriaceae. In this study, we report that purified Tsh(s) is capable of adhering to red blood cells, hemoglobin, and the extracellular matrix proteins fibronectin and collagen IV. We also demonstrate that Tsh(s) exerts proteolytic activity against casein, and we provide experimental evidence demonstrating that serine 259 is essential for the protease function. However, this residue is not required for adherence to substrates, and its replacement by an alanine does not abolish binding activity. In summary, our results demonstrate that Tsh is a bifunctional protein with both adhesive and proteolytic properties.