A maturase that specifically stabilizes and activates its cognate group I intron at high temperatures.
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.
State Key Laboratory of Virology, Department of Biochemistry and Molecular Biology, College of Life Sciences, Wuhan University, Wuhan, Hubei, China.
Dingding
D
Mo
Lingjia
L
Wu
Youzhi
Y
Xu
Jun
J
Ren
Long
L
Wang
Lin
L
Huang
Qi-Jia
QJ
Wu
Penghui
P
Bao
Mao-Hua
MH
Xie
Ping
P
Yin
Bi-Feng
BF
Liu
Yi
Y
Liang
Yi
Y
Zhang
D001483:Base Sequence; D004720:Endonucleases / Q000378:metabolism*; D007438:Introns / Q000235:genetics*; D012326:RNA Splicing; D020871:RNA Stability; D012329:RNA, Bacterial / Q000235:genetics; D013379:Substrate Specificity; D013696:Temperature; D013816:Thermodynamics; D046949:Thermotoga neapolitana / Q000201:enzymology / Q000235:genetics
D012329:RNA, Bacterial; D004720:Endonucleases