Author:
Ishigami Izumi,Carbajo Sergio,Zatsepin Nadia,Hikita Masahide,Conrad Chelsie E.,Nelson Garrett,Coe Jesse,Basu Shibom,Grant Thomas,Seaberg Matthew H.,Sierra Raymond G.,Hunter Mark S.,Fromme Petra,Fromme Raimund,Rousseau Denis L.,Yeh Syun-Ru
Abstract
AbstractCytochromecoxidase (CcO) is a large membrane-bound hemeprotein that catalyzes the reduction of dioxygen to water. Unlike classical dioxygen binding hemeproteins with a hemebgroup in their active sites, CcO has a unique binuclear center (BNC) comprised of a copper atom (CuB) and a hemea3iron, where O2binds and is reduced to water. CO is a versatile O2surrogate in ligand binding and escape reactions. Previous time-resolved spectroscopic studies of the CO complexes of bovine CcO (bCcO) revealed that photolyzing CO from the hemea3iron leads to a metastable intermediate (CuB-CO), where CO is bound to CuB, before it escapes out of the BNC. Here, with a time-resolved serial femtosecond X-ray crystallography-based pump-probe method, we detected a geminate photoproduct of the bCcO-CO complex, where CO is dissociated from the hemea3iron and moved to a temporary binding site midway between the CuBand the hemea3iron, while the locations of the two metal centers and the conformation of the Helix-X, housing the proximal histidine ligand of the hemea3iron, remain in the CO complex state. This new structure, combined with other reported structures of bCcO, allows the full definition of the ligand dissociation trajectory, as well as the associated protein dynamics.
Publisher
Cold Spring Harbor Laboratory
Cited by
1 articles.
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