Key Laboratory of Molecular Microbiology and Technology, Department of Microbiology, Nankai University, Ministry of Education, Tianjin, 300071, People's Republic of China.
Extremophiles. 2012 May;16(3):377-85. doi: 10.1007/s00792-012-0436-1. Epub 2012 Mar 9.
Numerous trehalose synthases (TreS) from thermophilic microorganisms have extra C-terminal domains. To determine the function of the N- and C-terminal domains of TreS from the thermophilic bacterium Meiothermus ruber CBS-01, the two domains were expressed. From the findings, the N-terminal domain from M. ruber was not active when compared with that from Thermus thermophilus, which had been studied previously. The circular dichroism spectrum showed that the secondary structure of N-terminal domain from M. ruber underwent a greater change than that of C terminus. In addition, the N-terminal domain from T. thermophilus and C terminus from M. ruber were fused. The fusion protein TSTtMr was more efficient and thermostable than the TreS from M. ruber. The N-terminal domain from M. ruber and C terminus from T. thermophilus were fused. The optimum temperature and thermostability of fusion protein TSMrTt were similar to the TreS from M. ruber. It was presumed that aside from the C-terminal domain, the N-terminal domain of TreS from thermophilic bacteria could influence thermostability. For the TreS from M. ruber, the mutant protein R392F led to a complete loss in activity, and R392A showed a sharp decrease in activity.
许多嗜热微生物的海藻糖合酶（TreS）都有额外的 C 末端结构域。为了确定来自嗜热细菌美嗜热单胞菌 CBS-01 的 TreS 的 N 末端和 C 末端结构域的功能，对这两个结构域进行了表达。研究结果表明，与先前研究过的嗜热栖热菌的海藻糖合酶相比，美嗜热单胞菌的 N 末端结构域没有活性。圆二色光谱表明，美嗜热单胞菌 N 末端结构域的二级结构变化大于 C 末端。此外，还融合了来自嗜热栖热菌的 N 末端结构域和来自美嗜热单胞菌的 C 末端结构域。融合蛋白 TSTtMr 的效率和热稳定性均高于来自美嗜热单胞菌的 TreS。融合了来自美嗜热单胞菌的 N 末端结构域和来自嗜热栖热菌的 C 末端结构域。融合蛋白 TSMrTt 的最适温度和热稳定性与来自美嗜热单胞菌的 TreS 相似。推测除了 C 末端结构域外，来自嗜热细菌的 TreS 的 N 末端结构域也可能影响热稳定性。对于来自美嗜热单胞菌的 TreS，突变蛋白 R392F 导致完全失去活性，而 R392A 则导致活性急剧下降。
