Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Gdansk 80-308, Poland.
Department of Biophysics, Institute of Experimental Physics, University of Warsaw, Warsaw 02-089, Poland.
Int J Biol Macromol. 2018 Apr 1;109:992-1005. doi: 10.1016/j.ijbiomac.2017.11.086. Epub 2017 Nov 16.
The HtrA proteins due to their proteolytic, and in many cases chaperone activity, efficiently counteract consequences of stressful conditions. In the environmental bacterium and nosocomial pathogen Stenotrophomonas maltophilia HtrA (HtrA) is induced as a part of adaptive response to host temperature (37°C). We examined the biochemical properties of HtrA and compared them with those of model HtrA from Escherichia coli. We found that HtrA is a protease and chaperone that operates over a wide range of pH and is highly active at temperatures between 35 and 37°C. The temperature-sensitive activity corresponded well with the lower thermal stability of the protein and weaker stability of the oligomer. Interestingly, the enzyme shows slightly different substrate cleavage specificity when compared to other bacterial HtrAs. A computational model of the three-dimensional structure of HtrA indicates differences in the S1 substrate specificity pocket and suggests weaker inter-trimer interactions when compared to HtrA. The observed features of HtrA suggest that this protein may play a protective role under stressful conditions acting both as a protease and a chaperone. The optimal temperatures for the protein activity may reflect the evolutionary adaptation of S. maltophilia to life in soil or aqueous environments, where the temperatures are usually much below 37°C.
HtrA 蛋白因其蛋白水解和在许多情况下的伴侣活性，能够有效地抵消应激条件的后果。在环境细菌和医院病原体嗜麦芽寡养单胞菌中，HtrA（HtrA）作为宿主温度（37°C）适应反应的一部分被诱导。我们研究了 HtrA 的生化特性，并将其与大肠杆菌模型 HtrA 进行了比较。我们发现 HtrA 是一种蛋白酶和伴侣，在广泛的 pH 值范围内起作用，在 35 至 37°C 之间的温度下具有很高的活性。温度敏感活性与蛋白质较低的热稳定性和低聚物稳定性非常吻合。有趣的是，与其他细菌 HtrAs 相比，该酶的底物切割特异性略有不同。HtrA 的三维结构计算模型表明，S1 底物特异性口袋存在差异，并表明与 HtrA 相比，三聚体之间的相互作用较弱。观察到的 HtrA 特征表明，该蛋白在应激条件下可能发挥保护作用，既作为蛋白酶又作为伴侣。该蛋白活性的最佳温度可能反映了嗜麦芽寡养单胞菌对土壤或水相环境中生活的进化适应，在这些环境中，温度通常远低于 37°C。
