A maturase that specifically stabilizes and activates its cognate group I intron at high temperatures

• Published in: Biochimie 2011-03, Vol.93 (3), p.533-541
• Main Authors: Mo, Dingding, Wu, Lingjia, Xu, Youzhi, Ren, Jun, Wang, Long, Huang, Lin, Wu, Qi-Jia, Bao, Penghui, Xie, Mao-Hua, Yin, Ping, Liu, Bi-Feng, Liang, Yi, Zhang, Yi
• Format: Article
• Language: English
• Subjects: Base Sequence; Endonucleases - metabolism; Introns - genetics; RNA Splicing; RNA Stability; RNA, Bacterial - genetics; Substrate Specificity; Temperature; Thermodynamics; Thermotoga; Thermotoga neapolitana - enzymology; Thermotoga neapolitana - genetics
• ISSN: 0300-9084; 1638-6183
• DOI: 10.1016/j.biochi.2010.11.008

Folding of large structured RNAs into their functional tertiary structures at high temperatures is challenging. Here we show that I-TnaI protein, a small LAGLIDADG homing endonuclease encoded by a group I intron from a hyperthermophilic bacterium, acts as a maturase that is essential for the catalytic activity of this intron at high temperatures and physiological cationic conditions. I-TnaI specifically binds to and induces tertiary packing of the P4–P6 domain of the intron; this RNA–protein complex might serve as a thermostable platform for active folding of the entire intron. Interestingly, the binding affinity of I-TnaI to its cognate intron RNA largely increases with temperature; over 30-fold stronger binding at higher temperatures relative to 37 °C correlates with a switch from an entropy-driven (37 °C) to an enthalpy-driven (55–60 °C) interaction mode. This binding mode may represent a novel strategy how an RNA binding protein can promote the function of its target RNA specifically at high temperatures. ► I-TnaI acts as a maturase on Thermotoga ribozyme. ► I-TnaI binds to the P4–P6 domain of the Thermotoga ribozyme. ► The binding affinity of I-TnaI to its cognate RNA increases with temperatures. ► The binding switches from entropy-driven (37 °C) to enthalpy-driven (55–60 °C).