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Title: Crystal structure of CO-bound cytochrome c oxidase determined by serial femtosecond X-ray crystallography at room temperature

Journal Article · · Proceedings of the National Academy of Sciences of the United States of America
 [1];  [2];  [3];  [4];  [2];  [2];  [2];  [5];  [6];  [6];  [6];  [2];  [2];  [1];  [1]
  1. Albert Einstein College of Medicine, Bronx, NY (United States)
  2. Arizona State Univ., Tempe, AZ (United States)
  3. Albert Einstein College of Medicine, Bronx, NY (United States); Institute of Materials Structure Science, Ibaraki (Japan)
  4. Arizona State Univ., Tempe, AZ (United States); National Cancer Institute, Frederick, MD (United States)
  5. State Univ. of New York at Buffalo, Buffalo, NY (United States)
  6. SLAC National Accelerator Lab., Menlo Park, CA (United States)

Here, cytochrome c oxidase (CcO), the terminal enzyme in the electron transfer chain, translocates protons across the inner mitochondrial membrane by harnessing the free energy generated by the reduction of oxygen to water. Several redox-coupled proton translocation mechanisms have been proposed, but they lack confirmation, in part from the absence of reliable structural information due to radiation damage artifacts caused by the intense synchrotron radiation. Here we report the room temperature, neutral pH (6.8), damage-free structure of bovine CcO (bCcO) in the carbon monoxide (CO)-bound state at a resolution of 2.3 Å, obtained by serial femtosecond X-ray crystallography (SFX) with an X-ray free electron laser. As a comparison, an equivalent structure was obtained at a resolution of 1.95 Å, from data collected at a synchrotron light source. In the SFX structure, the CO is coordinated to the heme a3 iron atom, with a bent Fe–C–O angle of ~142°. In contrast, in the synchrotron structure, the Fe–CO bond is cleaved; CO relocates to a new site near CuB, which, in turn, moves closer to the heme a3 iron by ~0.38 Å. Structural comparison reveals that ligand binding to the heme a3 iron in the SFX structure is associated with an allosteric structural transition, involving partial unwinding of the helix-X between heme a and a3, thereby establishing a communication linkage between the two heme groups, setting the stage for proton translocation during the ensuing redox chemistry.

Research Organization:
SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
AC02-76SF00515; GM098799; GM115773; GM095583; CHE-1404929; ABI-1565180; STC-1231306
OSTI ID:
1390295
Journal Information:
Proceedings of the National Academy of Sciences of the United States of America, Vol. 114, Issue 30; ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 36 works
Citation information provided by
Web of Science

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Distinct Pharmacological Properties of Gaseous CO and CO-Releasing Molecule in Human Platelets journal March 2021
Radiation chemists look at damage in redox proteins induced by X-rays journal May 2018
Macromolecular Nanocrystal Structural Analysis with Electron and X-Rays: A Comparative Review journal September 2019
Snapshot of an oxygen intermediate in the catalytic reaction of cytochrome c oxidase journal February 2019
X-ray free-electron laser: opportunities for drug discovery journal July 2018
Recent Advances in Ultrafast Structural Techniques journal April 2019
X-ray free electron laser: opportunities for drug discovery journal November 2017
Cytochrome c oxidase structures suggest a four-state stochastic pump mechanism journal January 2019
Insights into functions of the H channel of cytochrome c oxidase from atomistic molecular dynamics simulations journal November 2017