title: The multifaceted pyridoxal 5'-phosphate-dependent O-acetylserine sulfhydrylase.
abstract: Cysteine is the final product of the reductive sulfate assimilation pathway in bacteria and plants and serves as the precursor for all sulfur-containing biological compounds, such as methionine, S-adenosyl methionine, iron-sulfur clusters and glutathione. Moreover, in several microorganisms cysteine plays a role as a reducing agent, eventually counteracting host oxidative defense strategies. Cysteine is synthesized by the PLP-dependent O-acetylserine sulfhydrylase, a dimeric enzyme belonging to the fold type II, catalyzing a beta-replacement reaction. In this review, the spectroscopic properties, catalytic mechanism, three-dimensional structure, conformational changes accompanying catalysis, determinants of enzyme stability, role of selected amino acids in catalysis, and the regulation of enzyme activity by ligands and interaction with serine acetyltransferase, the preceding enzyme in the biosynthetic pathway, are described. Given the key biological role played by O-acetylserine sulfhydrylase in bacteria, inhibitors with potential antibiotic activity have been developed. This article is part of a Special Issue entitled: Pyridoxal Phospate Enzymology.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Parma, Parma, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Mozzarelli
authors.forename: Stefano
authors.initials: S
authors.lastname: Bettati
authors.forename: Barbara
authors.initials: B
authors.lastname: Campanini
authors.forename: Enea
authors.initials: E
authors.lastname: Salsi
authors.forename: Samanta
authors.initials: S
authors.lastname: Raboni
authors.forename: Ratna
authors.initials: R
authors.lastname: Singh
authors.forename: Francesca
authors.initials: F
authors.lastname: Spyrakis
authors.forename: Vidya Prasanna
authors.initials: VP
authors.lastname: Kumar
authors.forename: Paul F
authors.initials: PF
authors.lastname: Cook
mesh_terms: D055162:Biocatalysis; D003547:Cysteine Synthase / Q000378:metabolism*; D004795:Enzyme Stability; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D011489:Protein Denaturation; D011732:Pyridoxal Phosphate / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics
chemical_list: D011732:Pyridoxal Phosphate; D003547:Cysteine Synthase