4dcx
X-ray structure of NikA in complex with Fe(1R,2R)-N,N'-Bis(2-pyridylmethyl)-N,N'-dicarboxymethyl-1,2-cyclohexanediamineX-ray structure of NikA in complex with Fe(1R,2R)-N,N'-Bis(2-pyridylmethyl)-N,N'-dicarboxymethyl-1,2-cyclohexanediamine
Structural highlights
Function[NIKA_ECOLI] Involved in a nickel transport system, probably represents the nickel binder. Publication Abstract from PubMedUnderstanding the interaction of a protein with a relevant ligand is crucial for the design of an artificial metalloenzyme. Our own interest is focused on the synthesis of artificial monooxygenases. In an initial effort, we have used the periplasmic nickel-binding protein NikA from Escherichia coli and iron complexes in which N(2)Py(2) ligands (where Py is pyridine) have been varied in terms of charge, aromaticity, and size. Six "NikA/iron complex" hybrids have been characterized by X-ray crystallography, and their interactions and solution properties have been studied. The hybrids are stable as indicated by their K (d) values, which are all in the micromolar range. The X-ray structures show that the ligands interact with NikA through salt bridges with arginine residues and pi-stacking with a tryptophan residue. We have further characterized these interactions using quantum mechanical calculations and determined that weak CH/pi hydrogen bonds finely modulate the stability differences between hybrids. We emphasize the important role of the tryptophan residues. Thus, our study aims at the complete characterization of the factors that condition the interaction of an artificial ligand and a protein and their implications for catalysis. Besides its potential usefulness in the synthesis of artificial monooxygenases, our approach should be generally applicable in the field of artificial metalloenzymes. The structure of the periplasmic nickel-binding protein NikA provides insights for artificial metalloenzyme design.,Cherrier MV, Girgenti E, Amara P, Iannello M, Marchi-Delapierre C, Fontecilla-Camps JC, Menage S, Cavazza C J Biol Inorg Chem. 2012 Apr 21. PMID:22526565[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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