6UIZ

Artificial Iron Proteins: Modeling the Active Sites in Non-Heme Dioxygenases.

(2020) Inorg Chem 59: 6000-6009

• PubMed: 32309932 Search on PubMedSearch on PubMed Central
• DOI: https://doi.org/10.1021/acs.inorgchem.9b03791
• Primary Citation of Related Structures:  
  6UI0, 6UIU, 6UIY, 6UIZ, 6US6


• PubMed Abstract: 
  

  An important class of non-heme dioxygenases contains a conserved Fe binding site that consists of a 2-His-1-carboxylate facial triad. Results from structural biology show that, in the resting state, these proteins are six-coordinate with aqua ligands occupying the remaining three coordination sites. We have utilized biotin-streptavidin (Sav) technology to design new artificial Fe proteins (ArMs) that have many of the same structural features found within active sites of these non-heme dioxygenases. An Sav variant was isolated that contains the S ₁₁₂ E mutation, which installed a carboxylate side chain in the appropriate position to bind to a synthetic Fe ^II complex confined within Sav. Structural studies using X-ray diffraction (XRD) methods revealed a facial triad binding site that is composed of two N donors from the biotinylated ligand and the monodentate coordination of the carboxylate from S ₁₁₂ E. Two aqua ligands complete the primary coordination sphere of the Fe ^II center with both involved in hydrogen bond networks within Sav. The corresponding Fe ^III protein was also prepared and structurally characterized to show a six-coordinate complex with two exogenous acetato ligands. The Fe ^III protein was further shown to bind an exogenous azido ligand through replacement of one acetato ligand. Spectroscopic studies of the ArMs in solution support the results found by XRD.

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Organizational Affiliation: 

Department of Chemistry, 1102 Natural Science II, University of California, Irvine, California 92697, United States.