Key Laboratory for Space Bioscience and Space Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, 710072, Shaanxi, People's Republic of China.
College of Food Science, Agricultural and Animal Husbandry College of Tibet University, Linzhi, 860000, Xi Zang, People's Republic of China.
Cell Stress Chaperones. 2018 Jul;23(4):653-662. doi: 10.1007/s12192-018-0874-5. Epub 2018 Jan 22.
Small heat shock proteins (sHSPs) are heat shock proteins sized 12-43 kDa that can protect proteins from denaturation, particularly under high temperature; sHSPs thus increase the heat tolerance capability of an organisms enabling survival in adverse climates. sHSP20 is overexpressed in Oenococcus oeni in response to low temperatures. However, we found that overexpression of sHSP20 in Escherichia coli BL21 increased the microbial survival ratio at 50 °C by almost 2 h. Adding sHSP20 to the glutamate dehydrogenase solution significantly increased the stability of the enzyme at high temperature (especially at 60-70 °C), low pH values (especially below 6.0), and high concentration of metal ions of Ga, Zn, Mn, and Fe. Notably, the coexpression of sHSP20 significantly enhanced soluble expression of laccase from Phomopsis sp. XP-8 (CCTCCM209291) in E. coli without codon optimization, as well as the activity and heat stability of the expressed enzyme. In addition to the chaperone activity of sHSP20 in the gene containing host in vivo and the enzyme heat stability in vitro, our study indicated the capability of coexpression of sHSP20 to increase the efficiency of prokaryotic expression of fungal genes and the activity of expressed enzymes. Graphical abstract ᅟ.
小分子热休克蛋白（sHSPs）是分子量为 12-43 kDa 的热休克蛋白，能够保护蛋白质免于变性，特别是在高温下；因此，sHSPs 提高了生物体的耐热能力，使它们能够在恶劣的气候中生存。在低温下，Oenococcus oeni 中的 sHSP20 过表达。然而，我们发现，在 Escherichia coli BL21 中过表达 sHSP20 可使微生物在 50°C 下的存活率增加近 2 小时。向谷氨酸脱氢酶溶液中添加 sHSP20 可显著提高酶在高温（特别是 60-70°C）、低 pH 值（特别是低于 6.0）和高浓度金属离子 Ga、Zn、Mn 和 Fe 下的稳定性。值得注意的是，sHSP20 的共表达可显著提高未经密码子优化的 Phomopsis sp. XP-8（CCTCCM209291）漆酶在大肠杆菌中的可溶性表达以及表达酶的活性和热稳定性。除了 sHSP20 在体内含目的基因的宿主中的伴侣活性和酶的体外热稳定性外，我们的研究还表明 sHSP20 共表达能够提高真菌基因原核表达的效率和表达酶的活性。
