Deciphering the influence of the [4Fe–4S] cluster of tRNA thiolation enzymes on tRNA binding

Sensitivity of the [4Fe–4S] cluster of MmTtuI to the environment of the U8 target base in MmtRNA^Lys. (A) Chemical structure of 2-aminopurine (2AP) and its position (in black) in 2AP9-MmtRNA^Lys, adjacent to the target base U8 (in red). (B) Fluorescence spectra obtained at λ_ex = 320 nm of 2AP9-MmtRNA^Lys (0.5 µM). 2AP9-MmtRNA^Lys alone (in green), in the presence of apo-MmTtuI (2 µM) + 3 mM AMP-CPP (in blue) or in the presence of holo-MmTtuI (2 µM) + 3 mM AMP-CPP (in red). Apo-MmTtuI in the absence of 2AP9-MmtRNA^Lys (in black). (C) Region surrounding U8 in the AlphaFold3 model of MmtRNA^Lys (pTM score of 0.44). The target base U8 is shown in magenta.