PMID: 7664122
Malashkevich VN, Onuffer JJ, Kirsch JF, Jansonius JN
Alternating arginine-modulated substrate specificity in an engineered tyrosine aminotransferase.
Nat Struct Biol. 1995 Jul;2(7):548-53.
Mutation of six residues of Escherichia coli aspartate aminotransferase results in substantial acquisition of the transamination properties of tyrosine amino-transferase without loss of aspartate transaminase activity. X-ray crystallographic analysis of key inhibitor complexes of the hexamutant reveals the structural basis for this substrate selectivity. It appears that tyrosine aminotransferase achieves nearly equal affinities for a wide range of amino acids by an unusual conformational switch. An active-site arginine residue either shifts its position to electrostatically interact with charged substrates or moves aside to allow access of aromatic ligands.