Characterization of an exported protease from Shiga toxin-producing Escherichia coli
Characterization of an exported protease from Shiga toxin-producing Escherichia coli
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DOI：
10.1046/j.1365-2958.1997.5141874.x
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发表时间：
1997-08-01
影响因子：
3.6
通讯作者：
Chakraborty, T
中科院分区：
文献类型：
--
作者：
Djafari, S;Ebel, F;Chakraborty, T
由产滋贺毒素的大肠杆菌（STEC）分泌的新型高分子量蛋白质的基因已被克隆、测序并就其活性进行表征。这个基因，命名为pssA，是本地化的大质粒，也窝藏STEC溶血素操纵子，测序的一个区域，包括10 630个核苷酸的序列显示，侧翼的pssA基因是由不同的插入元件的几个残余。PssA蛋白作为142 kDa前体分子产生，在N-和C-末端加工后，其作为约104 kDa的成熟多肽释放到培养物上清液中。PssA的一级序列与来自不同革兰氏阴性病原体的自主转运的推定毒力因子家族高度相关，其中包括禽致病性E.大肠杆菌的SepA蛋白、福氏志贺菌的SepA蛋白和肠致病性大肠杆菌的EspC蛋白。杆菌所有四种蛋白质中存在的共同基序使人想起某些丝氨酸蛋白酶的催化中心。PssA（STEC分泌的蛋白酶）在基于酪蛋白的测定中确实显示丝氨酸蛋白酶活性，并且此外对Vero细胞具有细胞毒性。PssA和可能的Tsh家族的其他蛋白质的这种活性在细菌病原体感染粘膜细胞层期间可能具有功能重要性。
The gene for a novel, high molecular weight protein secreted by Shiga toxin-producing Escherichia coli (STEC) has been cloned, sequenced and characterized with respect to its activity. This gene, designated pssA, is localized on the large plasmid that also harbours the STEC haemolysin operon, Sequencing of a region comprising 10 630 nt revealed that the sequences flanking the pssA gene are composed of several remnants of different insertion elements. The PssA protein is produced as a 142 kDa precursor molecule that, after N- and C-terminal processing, is released into the culture supernatant as a mature polypeptide of approximately 104 kDa. The primary sequence of PssA is highly related to a family of autonomously transported putative virulence factors from different Gram-negative pathogens, which includes the Tsh protein of an avian-pathogenic E. coli strain, the SepA protein from Shigella flexneri and the EspC protein from enteropathogenic E. coli. A common motif present in all four proteins is reminiscent of the catalytic centre of certain serine proteases. PssA (protease Secreted by STEC) indeed shows serine protease activity in a casein-based assay and is moreover cytotoxic for Vero cells. This activity of PssA and probably of other proteins of the Tsh family may be of functional importance during infection of the mucosal cell layer by the bacterial pathogen.