6q58

Copper loading to a cytosolic copper storage protein from Streptomyces lividans (five coppers)

spinqualitylabelsall models 6q58, resolution 1.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6q58 is a 4 chain structure with sequence from Streptomyces lividans 1326. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CU1 Gene: SCO3281 (Streptomyces lividans 1326) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed The chemical basis for protecting organisms against the toxic effect imposed by excess cuprous ions is to constrain this through high-affinity binding sites that employ cuprous-thiolate coordination chemistries. In bacteria, a family of cysteine rich four helix-bundle proteins utilise thiolate chemistry to bind up to 80 cuprous ions. These proteins have been termed copper storage proteins (Csp). The present study investigates cuprous ion loading to the Csp from Streptomyces lividans (SlCsp) using a combination of X-ray crystallography, site-directed mutagenesis and stopped-flow reaction kinetics with either aquatic cuprous ions or a chelating donor. We illustrate that at low cuprous ion concentrations, copper is loaded exclusively into an outer core region of SlCsp via one end of the four helix-bundle, facilitated by a set of three histidine residues. X-ray crystallography reveals the existence of polynuclear cuprous-thiolate clusters culminating in the assembly of a tetranuclear [Cu4(mu2-S-Cys)4(Nudelta1-His)] cluster in the outer core. As more cuprous ions are loaded, the cysteine lined inner core of SlCsp fills with cuprous ions but in a fluxional and dynamic manner with no evidence for the assembly of further intermediate polynuclear cuprous-thiolate clusters as observed in the outer core. Using site-directed mutagenesis a key role for His107 in the efficient loading of cuprous ions from a donor is established. A model of copper loading to SlCsp is proposed and discussed. A histidine residue and a tetranuclear cuprous-thiolate cluster dominate the copper loading landscape of a copper storage protein from Streptomyces lividans.,Straw ML, Hough MA, Wilson MT, Worrall JAR Chemistry. 2019 May 21. doi: 10.1002/chem.201901411. PMID:31111982 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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