Aryl-alcohol oxidase protein sequence: a comparison with glucose oxidase and other FAD oxidoreductases

Aryl-alcohol oxidase (LAO), an FAD-dependent enzyme involved in lignin degr adation, has been cloned from Pleurotus eryngii. The AAO protein is compose d of 593 amino acids, 27 of which form a signal peptide. It shows 33% seque nce identity with glucose oxidase from Aspergillus niger and lower homology with other oxidoreductases. The predicted secondary structures of both enz ymes are very similar. For AAO, it is predicted to contain 13 putative alph a-helices and two major beta-sheets, each of the putative beta-sheets forme d by six beta-strands. The ADP binding site and the signature-2 consensus s equence of the glucose-methanol-choline (GMC) oxidoreductases were also pre sent. Moreover, residues potentially involved in catalysis and substrate bi nding were identified in the vicinity of the flavin ring. They include two histidines (H502 and H546) and several aromatic residues (Y78, Y92 and F501 ), as reported in other FAD oxidoreductases. (C) 2000 Elsevier Science B.V. All rights reserved.