Structures of <i>Arabidopsis thaliana</i> oxygen-sensing plant cysteine oxidases 4 and 5 enable targeted manipulation of their activity
Mark D. White, Laura Dalle Carbonare, Mikel Lavilla-Puerta, Sergio Iacopino, Martin P. Edwards, Kate Dunne, Elisabete Pires, Colin Levy, M.A. McDonough, Francesco Licausi, Emily Flashman
Abstract
to 1.24 and 1.91 Å resolution, respectively. The structures reveal that the PCOs comprise a cupin-like scaffold, which supports a central metal cofactor coordinated by three histidines. While this overall structure is consistent with other thiol dioxygenases, closer inspection of the active site indicates that other catalytic features are not conserved, suggesting that the PCOs may use divergent mechanisms to oxidize their substrates. Conservative substitution of two active site residues had dramatic effects on PCO4 function both in vitro and in vivo, through yeast and plant complementation assays. Collectively, our data identify key structural elements that are required for PCO activity and provide a platform for engineering crops with improved hypoxia tolerance.