RNA Chaperone Function of a Universal Stress Protein in Arabidopsis Confers Enhanced Cold Stress Tolerance in Plants

• Main Authors: Sarah Mae Boyles Melencion, Yong Hun Chi, Thuy Thi Pham, Seol Ki Paeng, Seong Dong Wi, Changyu Lee, Seoung Woo Ryu, Sung Sun Koo, Sang Yeol Lee
• Format: Article
• Language: English
• Published: MDPI AG 2017-11-01
• Series: International Journal of Molecular Sciences
• Subjects: Arabidopsis thaliana universal stress protein (AtUSP); DNA- and RNA-binding activity; nucleic acid-melting activity; anti-termination activity; enhanced cold tolerance; RNA chaperone
• Online Access: https://www.mdpi.com/1422-0067/18/12/2546

The physiological function of Arabidopsis thaliana universal stress protein (AtUSP) in plant has remained unclear. Thus, we report here the functional role of the Arabidopsis universal stress protein, AtUSP (At3g53990). To determine how AtUSP affects physiological responses towards cold stress, AtUSP overexpression (AtUSP OE) and T-DNA insertion knock-out (atusp, SALK_146059) mutant lines were used. The results indicated that AtUSP OE enhanced plant tolerance to cold stress, whereas atusp did not. AtUSP is localized in the nucleus and cytoplasm, and cold stress significantly affects RNA metabolism such as by misfolding and secondary structure changes of RNA. Therefore, we investigated the relationship of AtUSP with RNA metabolism. We found that AtUSP can bind nucleic acids, including single- and double-stranded DNA and luciferase mRNA. AtUSP also displayed strong nucleic acid-melting activity. We expressed AtUSP in RL211 Escherichia coli, which contains a hairpin-loop RNA structure upstream of chloramphenicol acetyltransferase (CAT), and observed that AtUSP exhibited anti-termination activity that enabled CAT gene expression. AtUSP expression in the cold-sensitive Escherichia coli (E. coli) mutant BX04 complemented the cold sensitivity of the mutant cells. As these properties are typical characteristics of RNA chaperones, we conclude that AtUSP functions as a RNA chaperone under cold-shock conditions. Thus, the enhanced tolerance of AtUSP OE lines to cold stress is mediated by the RNA chaperone function of AtUSP.