4bpy
Crystal structure of the C90A mutant of the Sco copper chaperone protein from Streptomyces lividansCrystal structure of the C90A mutant of the Sco copper chaperone protein from Streptomyces lividans
Structural highlights
FunctionPublication Abstract from PubMedIn Streptomyces lividans an extracytoplasmic copper-binding Sco protein plays a role in two unlinked processes: (i) initiating a morphological development switch and (ii) facilitating the co-factoring of the CuA domain of CcO (cytochrome c oxidase). How Sco obtains copper once secreted to the extracytoplasmic environment is unknown. In the present paper we report on a protein possessing an HX6MX21HXM motif that binds a single cuprous ion with subfemtomolar affinity. High-resolution X-ray structures of this extracytoplasmic copper chaperone-like protein (ECuC) in the apo- and Cu(I)-bound states reveal that the latter possesses a surface-accessible cuprous-ion-binding site located in a dish-shaped region of beta-sheet structure. A cuprous ion is transferred under a favourable thermodynamic gradient from ECuC to Sco with no back transfer occurring. The ionization properties of the cysteine residues in the Cys86xxxCys90 copper-binding motif of Sco, together with their positional locations identified from an X-ray structure of Sco, suggests a role for Cys86 in initiating an inter-complex ligand-exchange reaction with Cu(I)-ECuC. Generation of the genetic knockouts, Deltasco, Deltaecuc and Deltasco/ecuc, and subsequent in vivo assays lend support to the existence of a branched extracytoplasmic copper-trafficking pathway in S. lividans. One branch requires both Sco and to a certain extent ECuC to cofactor the CuA domain, whereas the other uses only Sco to deliver copper to a cuproenzyme to initiate morphological development. Structural and mechanistic insights into an extracytoplasmic copper trafficking pathway in Streptomyces lividans.,Blundell KL, Hough MA, Vijgenboom E, Worrall JA Biochem J. 2014 May 1;459(3):525-38. doi: 10.1042/BJ20140017. PMID:24548299[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
|
| ||||||||||||||||||