The generation of a 1-hydroxy-2-naphthoate 1,2-dioxygenase by single point mutations of salicylate 1,2-dioxygenase - Rational design of mutants and the crystal structures of the A85H and W104Y variants

The crystal structures of the A85H and W104Y variants were solved and analyzed. The substitution of Ala85 with a histidine residue caused significant changes in the orientation of the loop containing this residue which is involved in the active site closing upon substrate binding. In SDO A85H this specific loop shifts away from the active site and thus opens the cavity favoring the binding of bulkier substrates. Since this loop also interacts with the N-terminal residues of the vicinal subunit, the structure and packing of the holoenzyme might be also affected.