title: Structure-Function Relationships in l-Amino Acid Deaminase, a Flavoprotein Belonging to a Novel Class of Biotechnologically Relevant Enzymes.
abstract: l-Amino acid deaminase from Proteus myxofaciens (PmaLAAD) is a membrane flavoenzyme that catalyzes the deamination of neutral and aromatic l-amino acids into α-keto acids and ammonia. PmaLAAD does not use dioxygen to re-oxidize reduced FADH2 and thus does not produce hydrogen peroxide; instead, it uses a cytochrome b-like protein as an electron acceptor. Although the overall fold of this enzyme resembles that of known amine or amino acid oxidases, it shows the following specific structural features: an additional novel α+β subdomain placed close to the putative transmembrane α-helix and to the active-site entrance; an FAD isoalloxazine ring exposed to solvent; and a large and accessible active site suitable to bind large hydrophobic substrates. In addition, PmaLAAD requires substrate-induced conformational changes of part of the active site, particularly in Arg-316 and Phe-318, to achieve the correct geometry for catalysis. These studies are expected to pave the way for rationally improving the versatility of this flavoenzyme, which is critical for biocatalysis of enantiomerically pure amino acids.
authors.affiliation: From the Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi deII'Insubria, via J. H. Dunant 3, 21100 Varese.
authors.forename: Paolo
authors.initials: P
authors.lastname: Motta
authors.affiliation: From the Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi deII'Insubria, via J. H. Dunant 3, 21100 Varese, The Protein Factory, Politecnico di Milano and Università degli Studi deII'Insubria, 21100 Varese, and gianluca.molla@uninsubria.it.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Molla
authors.affiliation: From the Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi deII'Insubria, via J. H. Dunant 3, 21100 Varese, The Protein Factory, Politecnico di Milano and Università degli Studi deII'Insubria, 21100 Varese, and.
authors.forename: Loredano
authors.initials: L
authors.lastname: Pollegioni
authors.affiliation: the Dipartimento di Bioscienze, Università degli Studi di Milano, via Celoria 26, 20133 Milano, Italy marco.nardini@unimi.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Nardini
mesh_terms: D000581:Amidohydrolases / Q000737:chemistry* / Q000378:metabolism; D000596:Amino Acids / Q000737:chemistry* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry* / Q000378:metabolism; D005420:Flavoproteins / Q000737:chemistry* / Q000378:metabolism; D011511:Proteus / Q000201:enzymology*
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D005420:Flavoproteins; D005182:Flavin-Adenine Dinucleotide; D000581:Amidohydrolases
keywords: L-amino acid oxidase; conformational change; enzyme structure; flavoprotein; membrane-bound enzyme; protein engineering; structure-function; x-ray crystallography