Crystal structure and biochemical features of dye-decolorizing peroxidase YfeX from Escherichia coli O157 Asp143 and Arg232 play divergent roles toward different substrates

Abstract

YfeX from Escherichia coli O157 is a bacterial dye-decolorizing peroxidase that represents both dye-decoloring activity and typical peroxidase activity. We reported the crystal structure of YfeX bound to heme at 2.09 Å resolution. The YfeX monomer resembles a ferredoxin-like fold and contains two domains. The three conserved residues surrounding the heme group are His²¹⁵, Asp¹⁴³ and Arg²³². His²¹⁵ functions as the proximal axial ligand of the heme iron atom. Biochemical data show that the catalytic significance of the conserved Asp¹⁴³ and Arg²³² depends on the substrate types and that YfeX may adopt various catalytic mechanisms toward divergent substrates. In addition, it is observed that an access tunnel spans from the protein molecular surface to the heme distal region, it serves as the passageway for the entrance and binding of the H₂O₂.

Keywords: ABTS; Crystal structure; Dye-decolorizing peroxidase; Guaiacol; Reactive blue 19; YfeX.