1I4Z

THE CRYSTAL STRUCTURE OF PHASCOLOPSIS GOULDII L98Y METHEMERYTHRIN

Summary for 1I4Z

• Entry DOI: 10.2210/pdb1i4z/pdb
• Related: 1I4Y
• Descriptor: METHEMERYTHRIN, MU-OXO-DIIRON (3 entities in total)
• Functional Keywords: hemerythrin, oxygen binding, diiron, mutation, four-helix bundle, oxygen storage-transport complex, oxygen storage/transport
• Biological source: Phascolopsis gouldii
• Total number of polymer chains: 8
• Total formula weight: 110432.73

Authors

Farmer, C.S.,Kurtz Jr., D.M.,Liu, Z.-J.,Wang, B.C.,Rose, J. (deposition date: 2001-02-23, release date: 2001-03-21, Last modification date: 2024-04-03)

Primary citation

Farmer, C.S.,Kurtz Jr., D.M.,Liu, Z.J.,Wang, B.C.,Rose, J.,Ai, J.,Sanders-Loehr, J.
The crystal structures of Phascolopsis gouldii wild type and L98Y methemerythrins: structural and functional alterations of the O2 binding pocket.
J.Biol.Inorg.Chem., 6:418-429, 2001

PubMed Abstract: Reported are the X-ray crystal structures of recombinant Phascolopsis gouldii methemerythrin (1.8-A resolution) and the structure of an O2-binding-pocket mutant, L98Y methemerythrin (2.1-A resolution). The L98Y hemerythrin (Hr) has a greatly enhanced O2 affinity, a slower O2 dissociation rate, a larger solvent deuterium isotope effect on this rate, and a greater resistance to autoxidation relative to the wild-type protein. The crystal structures show that the hydrophobic binding pocket of Hr can accommodate substitution of a leucyl by a tyrosyl side chain with relatively minor structural rearrangements. UV/vis and resonance Raman spectra show that in solution L98Y methemerythrin contains a mixture of two diiron site structures differing by the absence or presence of an Fe(III)-coordinated phenolate. However, in the crystal, only one L98Y diiron site structure is seen, in which the Y98 hydroxyl is not a ligand, but instead forms a hydrogen bond to a terminal hydroxo/aqua ligand to the nearest iron. Based on this crystal structure, we propose that in the oxy form of L98Y hemerythrin the non-polar nature of the binding pocket favors localization of the Y98 hydroxyl near the O2 binding site, where it can donate a hydrogen bond to the hydroperoxo ligand. The stabilizing Y98OH-O2H-interaction would account for all of the altered O2 binding properties of L98Y Hr listed above.

PubMed: 11372200
DOI: 10.1007/s007750100218

Experimental method

X-RAY DIFFRACTION (2.1 Å)