Structural highlights
Publication Abstract from PubMedAn 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 S112E 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 S112E. 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. Artificial Iron Proteins: Modeling the Active Sites in Non-Heme Dioxygenases.,Miller KR, Paretsky JD, Follmer AH, Heinisch T, Mittra K, Gul S, Kim IS, Fuller FD, Batyuk A, Sutherlin KD, Brewster AS, Bhowmick A, Sauter NK, Kern J, Yano J, Green MT, Ward TR, Borovik AS Inorg Chem. 2020 May 4;59(9):6000-6009. doi: 10.1021/acs.inorgchem.9b03791. Epub , 2020 Apr 20. PMID:32309932[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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