Figure 1.

Kti12 resembles PSTK both structurally and functionally. (A) Structure of a CtKti12_NTD locked in a transition state of ATP hydrolysis shown in a cartoon representation. Aluminum fluoride, a hydrolysis transition state mimetic (magenta and cyan) and magnesium (green sphere) are highlighted. The protein core consists of a single β-sheet composed of five parallel β-strands (dark blue). Domain architectures of CtKti12 and ScKti12 are similar to that of MjPSTK. ATPase motifs located on the N-terminal domain (NTD) of Kti12 (blue) and PSTK (red); C-terminal domain (CTD; yellow). (B) Structure of CtKti12_NTD (blue) resembles the one of MjPSTK_NTD bound to tRNA^Sec (red; PDB ID 3ADB). The 3′ CCA of tRNA^Sec is inserted into the PSTK_NTD while the tRNA body is mainly held by PSTK_CTD (yellow). The anticodon region (green) is not involved in this interaction. C. Binding affinity of CtKti12 with bulk yeast tRNA was examined by electrophoretic mobility shift assay (EMSA) using 5% native PAGE. Free tRNA and tRNA in complex with CtKti12-FL or CtKti12_CTD were visualized using SYBR-Gold. Both full-length (FL) protein and CtKti12_CTD bind tRNA in a PSTK-like fashion.