title: How the local geometry of the Cu-binding site determines the thermal stability of blue copper proteins.
abstract: Identifying the factors that govern the thermal resistance of cupredoxins is essential for understanding their folding and stability, and for improving our ability to design highly stable enzymes with potential biotechnological applications. Here, we show that the thermal unfolding of plastocyanins from two cyanobacteria--the mesophilic Synechocystis and the thermophilic Phormidium--is closely related to the short-range structure around the copper center. Cu K-edge X-ray absorption spectroscopy shows that the bond length between Cu and the S atom from the cysteine ligand is a key structural factor that correlates with the thermal stability of the cupredoxins in both oxidized and reduced states. These findings were confirmed by an additional study of a site-directed mutant of Phormidium plastocyanin showing a reverse effect of the redox state on the thermal stability of the protein.
authors.affiliation: Instituto de Ciencia de Materiales de Aragón, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, 50009 Zaragoza, Spain. jchaboy@unizar.es
authors.forename: Jesús
authors.initials: J
authors.lastname: Chaboy
authors.forename: Sofía
authors.initials: S
authors.lastname: Díaz-Moreno
authors.forename: I
authors.initials: I
authors.lastname: Díaz-Moreno
authors.forename: Miguel A
authors.initials: MA
authors.lastname: De la Rosa
authors.forename: Antonio
authors.initials: A
authors.lastname: Díaz-Quintana
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D003300:Copper / Q000737:chemistry / Q000378:metabolism*; D000458:Cyanobacteria; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism; D004579:Electron Transport; D008024:Ligands; D008958:Models, Molecular; D009154:Mutation; D010970:Plastocyanin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D055550:Protein Stability; D058767:Protein Unfolding; D013455:Sulfur / Q000737:chemistry; D013696:Temperature; D056928:X-Ray Absorption Spectroscopy
chemical_list: D001426:Bacterial Proteins; D008024:Ligands; D013455:Sulfur; D003300:Copper; D010970:Plastocyanin; D003545:Cysteine