A maturase that specifically stabilizes and activates its cognate group I intron 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).