Taranov V V, Zlobin N E, Evlakov K I, Shamustakimova A O, Babakov A V
All-Russia Research Institute of Agricultural Biotechnology, Moscow, 127550, Russia.
Biochemistry (Mosc). 2018 Nov;83(11):1369-1379. doi: 10.1134/S000629791811007X.
Plant cold shock domain proteins (CSDPs) are DNA/RNA-binding proteins. CSDPs contain the conserved cold shock domain (CSD) in the N-terminal part and a varying number of the CCHC-type zinc finger (ZnF) motifs alternating with glycine-rich regions in the C-terminus. CSDPs exhibit RNA chaperone and RNA-melting activities due to their nonspecific interaction with RNA. At the same time, there are reasons to believe that CSDPs also interact with specific RNA targets. In the present study, we used three recombinant CSDPs from the saltwater cress plant (Eutrema salsugineum) - EsCSDP1, EsCSDP2, EsCSDP3 with 6, 2, and 7 ZnF motifs, respectively, and showed that their nonspecific interaction with RNA is determined by their C-terminal fragments. All three proteins exhibited high affinity to the single-stranded regions over four nucleotides long within RNA oligonucleotides. The presence of guanine in the single- or double-stranded regions was crucial for the interaction with CSDPs. Complementation test using E. coli BX04 cells lacking four cold shock protein genes (ΔcspA, ΔcspB, ΔcspE, ΔcspG) revealed that the specific binding of plant CSDPs with RNA is determined by CSD.
植物冷休克结构域蛋白（CSDPs）是DNA/RNA结合蛋白。CSDPs在N端含有保守的冷休克结构域（CSD），在C端含有数量不等的CCHC型锌指（ZnF）基序，与富含甘氨酸的区域交替出现。由于CSDPs与RNA的非特异性相互作用，它们表现出RNA伴侣和RNA解链活性。同时，有理由相信CSDPs也与特定的RNA靶标相互作用。在本研究中，我们使用了来自盐芥植物（Eutrema salsugineum）的三种重组CSDPs——EsCSDP1、EsCSDP2、EsCSDP3，分别具有6、2和7个ZnF基序，并表明它们与RNA的非特异性相互作用由其C端片段决定。所有这三种蛋白质对RNA寡核苷酸中长度超过四个核苷酸的单链区域表现出高亲和力。单链或双链区域中鸟嘌呤的存在对于与CSDPs的相互作用至关重要。使用缺乏四个冷休克蛋白基因（ΔcspA、ΔcspB、ΔcspE、ΔcspG）的大肠杆菌BX04细胞进行的互补试验表明，植物CSDPs与RNA的特异性结合由CSD决定。
