title: Open conformation of human DOPA decarboxylase reveals the mechanism of PLP addition to Group II decarboxylases.
abstract: DOPA decarboxylase, the dimeric enzyme responsible for the synthesis of neurotransmitters dopamine and serotonin, is involved in severe neurological diseases such as Parkinson disease, schizophrenia, and depression. Binding of the pyridoxal-5'-phosphate (PLP) cofactor to the apoenzyme is thought to represent a central mechanism for the regulation of its activity. We solved the structure of the human apoenzyme and found it exists in an unexpected open conformation: compared to the pig kidney holoenzyme, the dimer subunits move 20 Å apart and the two active sites become solvent exposed. Moreover, by tuning the PLP concentration in the crystals, we obtained two more structures with different conformations of the active site. Analysis of three-dimensional data coupled to a kinetic study allows to identify the structural determinants of the open/close conformational change occurring upon PLP binding and thereby propose a model for the preferential degradation of the apoenzymes of Group II decarboxylases.
authors.affiliation: Dipartimento di Scienze Biochimiche A. Rossi Fanelli, Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185 Rome, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Giardina
authors.forename: Riccardo
authors.initials: R
authors.lastname: Montioli
authors.forename: Stefano
authors.initials: S
authors.lastname: Gianni
authors.forename: Barbara
authors.initials: B
authors.lastname: Cellini
authors.forename: Alessandro
authors.initials: A
authors.lastname: Paiardini
authors.forename: Carla Borri
authors.initials: CB
authors.lastname: Voltattorni
authors.forename: Francesca
authors.initials: F
authors.lastname: Cutruzzolà
mesh_terms: D000818:Animals; D001053:Apolipoproteins / Q000737:chemistry; D020134:Catalytic Domain; D018360:Crystallography, X-Ray / Q000379:methods; D004296:Dopa Decarboxylase / Q000737:chemistry* / Q000235:genetics*; D004926:Escherichia coli / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods; D020035:Holoenzymes / Q000737:chemistry; D006801:Humans; D007668:Kidney; D007700:Kinetics; D008968:Molecular Conformation; D011485:Protein Binding; D011487:Protein Conformation; D012545:Schiff Bases / Q000737:chemistry; D013552:Swine
chemical_list: D001053:Apolipoproteins; D020035:Holoenzymes; D012545:Schiff Bases; D004296:Dopa Decarboxylase