UK Centre for Astrobiology, SUPA School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh EH9 3FD, U.K.
Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, U.K.
Biosci Rep. 2021 Apr 30;41(4). doi: 10.1042/BSR20210336.
Understanding the characteristics that define temperature-adapted enzymes has been a major goal of extremophile enzymology in recent decades. In the present study, we explore these characteristics by comparing psychrophilic, mesophilic, and thermophilic enzymes. Through a meta-analysis of existing data, we show that psychrophilic enzymes exhibit a significantly larger gap (Tg) between their optimum and melting temperatures compared with mesophilic and thermophilic enzymes. These results suggest that Tg may be a useful indicator as to whether an enzyme is psychrophilic or not and that models of psychrophilic enzyme catalysis need to account for this gap. Additionally, by using predictive protein stability software, HoTMuSiC and PoPMuSiC, we show that the deleterious nature of amino acid substitutions to protein stability increases from psychrophiles to thermophiles. How this ultimately affects the mutational tolerance and evolutionary rate of temperature adapted organisms is currently unknown.
了解定义适温酶特性的特点一直是近几十年来极端微生物酶学的主要目标。在本研究中，我们通过比较嗜冷酶、嗜温酶和嗜热酶来探究这些特性。通过对现有数据的元分析，我们表明与嗜温酶和嗜热酶相比，嗜冷酶的最适温度和熔点之间的差距（Tg）明显更大。这些结果表明，Tg 可能是一个有用的指标，可以判断一个酶是否为嗜冷酶，并且嗜冷酶催化的模型需要考虑到这种差距。此外，我们使用预测蛋白稳定性软件 HoTMuSiC 和 PoPMuSiC 表明，氨基酸取代对蛋白质稳定性的有害性质从嗜冷菌到嗜热菌逐渐增加。这最终如何影响适应温度的生物体的突变耐受性和进化速度目前尚不清楚。
