tRNA‐Monooxygenase EnzymeMiaE

Abstract

MiaE is a diiron‐containing monooxygenase that catalyzes the O 2 ‐dependent posttranscriptional allylic hydroxylation of a hypermodified nucleotide 2‐methylthio‐ N 6 ‐(4‐hydroxyisopentenyl)‐adenosine‐37 at position 37 of selected tRNA molecules to produce 2‐methylthio‐ N 6 ‐(4‐hydroxyisopentenyl)‐adenosine‐37. The structure of MiaE consists of a four α‐helix bundle fold housing a catalytic diiron domain. A positively charged surface patch bordering the active site entrance is likely to be involved in the early contacts with the tRNA substrate. A docking model of the MiaE/tRNA complex combined with site‐directed mutagenesis and in vivo activity reveals the importance of a flexible noncanonical region of MiaE for substrate tRNA recognition. A hydrophobic tunnel, conserved among the MiaE enzymes of different organisms, is described to be the pathway that transports the oxygen molecule from solvent to the diiron cluster. The active site consists of two bridged iron ions in diferric state [FeIIIOFeIII] with an octahedral coordination.

The High-Pressure Freezing Laboratory for Macromolecular Crystallography (HPMX), an ancillary tool for the macromolecular crystallography beamlines at the ESRF

“…The primary application for the use of pressurized gases is the mapping of surfaces and internal structural voids present in proteins (Carpentier et al, 2020(Carpentier et al, , 2022Engilberge et al, 2020;Markova et al, 2020;Colloc'h et al, 2017;Kalms et al, 2016;Ardiccioni et al, 2019;Zacarias et al, 2020;Melnikov et al, 2022;Montet et al, 1997). These empty volumes play crucial roles in conformational flexibility and in molecular mechanisms that allow biomacromolecules to fulfil their function.…”