title: A left-handed crossover involved in amidohydrolase catalysis. Crystal structure of Erwinia chrysanthemi L-asparaginase with bound L-aspartate.
abstract: The crystal structure of L-asparaginase from Erwinia chrysanthemi in the presence and absence of L-aspartate was determined at 1.8 A resolution. Conserved residues in a left-handed crossover (a rare occurrence in protein structures) link pairs of dimers into the catalytically active tetrameric form of the enzyme. The structure of ErA containing bound aspartic acid shows that this unusual strand connectivity is an essential part of the active site architecture, responsible for releasing the product of the enzymatic hydrolysis. The orientation of the bound aspartate indicates for the first time a threonine residue as a catalytic nucleophile.
authors.affiliation: Macromolecular Structure Laboratory, NCI-FCRDC, Frederick, MD 21702.
authors.forename: M
authors.initials: M
authors.lastname: Miller
authors.forename: J K
authors.initials: JK
authors.lastname: Rao
authors.forename: A
authors.initials: A
authors.lastname: Wlodawer
authors.forename: M R
authors.initials: MR
authors.lastname: Gribskov
mesh_terms: D000581:Amidohydrolases / Q000378:metabolism*; D000595:Amino Acid Sequence; D001215:Asparaginase / Q000737:chemistry* / Q000378:metabolism; D001224:Aspartic Acid / Q000378:metabolism*; D001665:Binding Sites; D002384:Catalysis; D017124:Conserved Sequence; D016974:Dickeya chrysanthemi / Q000201:enzymology*; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
chemical_list: D001224:Aspartic Acid; D000581:Amidohydrolases; D001215:Asparaginase