GLUCOSE-OXIDASE FROM PENICILLIUM AMAGASAKIENSE - PRIMARY STRUCTURE AND COMPARISON WITH OTHER GLUCOSE-METHANOL-CHOLINE (GMC) OXIDOREDUCTASES

The complete amino acid sequence of glucose oxidase from Penicillium a magasakiense was determined by Edman degradation and mass spectrometry of peptide fragments derived from three different specific proteolyti c digests and a cyanogen bromide cleavage. The complete sequence of ea ch monomer comprises 587 amino acid residues, contains three cysteine residues, and seven potential N-glycosylation sites, of which at least five were confirmed to be glycosylated. Glucose oxidase from P. amaga sakiense shows a high degree of identity (66%) and 79% similarity to g lucose oxidase from Aspergillus niger, and is a member of the glucose- methanol-choline (GMC) oxidoreductase family. The tertiary structures of glucose oxidase from A. niger and cholesterol oxidase from Brevibac terium sterolicum were superimposed to provide a template for the sequ ence comparison of members of the GMC family. The general topology of the GMC oxidoreductases is conserved, with the exception of the presen ce of an active site lid in cholesterol oxidase and the insertion of a dditional structural elements in the substrate-binding domain of alcoh ol oxidase. The overall structure can be divided into five distinct se quence regions: FAD-binding domain, extended FAD-binding domain, flavi n attachment loop and intermediate region, FAD covering lid, and subst rate-binding domain. The FAD-binding and the extended FAD-binding doma ins are composed of several separate sequence regions. The other three regions each comprise a single contiguous sequence. Four major consen sus patterns have been identified, including the nucleotide-binding co nsensus sequence close to their N-termini. The functions of the two mo tifs recently selected by the Genetics Computer Group, Madison, Wiscon sin, as additional signature patterns of the GMC oxidoreductases are d iscussed. The other consensus patterns belong to either the FAD-bindin g or the extended FAD-binding domain. In addition, the roles of conser ved residues are discussed wherever possible.