Property of cold inducible DEAD-box RNA helicase in hyperthermophilic archaea.
TK0306 (Tk-DeaD) of hyperthermophilic archaeon Thermococcus kodakaraensis is annotated as the DEAD-box helicase gene; nevertheless, its ortholog has not been identified in closely related genera, Pyrococcus spp., which generally grow at higher temperature than T. kodakaraensis, suggesting that the cold-inducible RNA helicase of Tk-DeaD functions under cold stress conditions. Quantitative RT-PCR revealed that Tk-deaD was more dominantly transcribed at 60 degrees C than at 85 degrees C and 93 degrees C in both logarithmic and stationary phases. Immunoblot analyses revealed that Tk-DeaD was detected only in logarithmic-phase cells cultivated at 60 degrees C but hardly detected at 85 degrees C and 93 degrees C in both phases. Tk-DeaD expression is, hence, post-transcriptionally regulated and appears under vigorous growth conditions at 60 degrees C. Recombinant Tk-DeaD purified to homogeneity started to unfold at 20 degrees C, fully unfolded at 70 degrees C, and exhibited maximal ATPase activity and unwinding activity specific for single-strand paired RNA at 50 degrees C, which is lower than the growth limit of T. kodakaraensis.
Shimada
Yoko
Y
Department of Bioscience, Graduate School of Science and Technology, Kwansei-Gakuin University, 2-1 Gakuen, Sanda, Hyogo, Japan.
Fukuda
Wakao
W
Akada
Yohei
Y
Ishida
Mayumi
M
Nakayama
Junichi
J
Imanaka
Tadayuki
T
Fujiwara
Shinsuke
S
D001483:Base Sequence; D003080:Cold Temperature; D053487:DEAD-box RNA Helicases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019848:Gene Expression Regulation, Archaeal; D008969:Molecular Sequence Data; D011487:Protein Conformation; D019712:Thermococcus / Q000201:enzymology* / Q000235:genetics
D053487:DEAD-box RNA Helicases