Cresser-Brown Joel, Rizkallah Pierre, Jin Yi, Roth Christian, Miller David J, Allemann Rudolf K
School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, UK.
Carbohydrates: Structure and Function, Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Arnimallee 22, 14195 Berlin, Germany.
Acta Crystallogr F Struct Biol Commun. 2020 Feb 1;76(Pt 2):81-85. doi: 10.1107/S2053230X20001181. Epub 2020 Feb 5.
Calpain is a Ca-activated, heterodimeric cysteine protease consisting of a large catalytic subunit and a small regulatory subunit. Dysregulation of this enzyme is involved in a range of pathological conditions such as cancer, Alzheimer's disease and rheumatoid arthritis, and thus calpain I is a drug target with potential therapeutic applications. Difficulty in the production of this enzyme has hindered structural and functional investigations in the past, although heterodimeric calpain I can be generated by Escherichia coli expression in low yield. Here, an unexpected structure discovered during crystallization trials of heterodimeric calpain I (CAPN1C115S + CAPNS1ΔGR) is reported. A novel co-crystal structure of the PEF(S) domain from the dissociated regulatory small subunit of calpain I and the RNA-binding chaperone Hfq, which was likely to be overproduced as a stress response to the recombinant expression conditions, was obtained, providing unexpected insight in the chaperone function of Hfq.
钙蛋白酶是一种钙激活的异二聚体半胱氨酸蛋白酶，由一个大的催化亚基和一个小的调节亚基组成。这种酶的失调与一系列病理状况有关，如癌症、阿尔茨海默病和类风湿性关节炎，因此钙蛋白酶I是一个具有潜在治疗应用价值的药物靶点。过去，这种酶的生产困难阻碍了其结构和功能研究，尽管异二聚体钙蛋白酶I可以通过大肠杆菌表达以低产量产生。在此，报道了在异二聚体钙蛋白酶I（CAPN1C115S + CAPNS1ΔGR）的结晶试验中发现的一种意外结构。获得了钙蛋白酶I解离的调节小亚基的PEF(S)结构域与RNA结合伴侣Hfq的一种新型共晶体结构，Hfq可能作为对重组表达条件的应激反应而过量产生，这为Hfq的伴侣功能提供了意外的见解。
