bims-resufa Biomed news
on Respiratory supercomplex factors
Issue of 2019‒03‒03
one paper selected by
Vera Strogolova
Marquette University

  1. Proc Natl Acad Sci U S A. 2019 Feb 26. 116(9): 3572-3577
    Ishigami I, Lewis-Ballester A, Echelmeier A, Brehm G, Zatsepin NA, Grant TD, Coe JD, Lisova S, Nelson G, Zhang S, Dobson ZF, Boutet S, Sierra RG, Batyuk A, Fromme P, Fromme R, Spence JCH, Ros A, Yeh SR, Rousseau DL.
      Cytochrome c oxidase (CcO) reduces dioxygen to water and harnesses the chemical energy to drive proton translocation across the inner mitochondrial membrane by an unresolved mechanism. By using time-resolved serial femtosecond crystallography, we identified a key oxygen intermediate of bovine CcO. It is assigned to the PR-intermediate, which is characterized by specific redox states of the metal centers and a distinct protein conformation. The heme a 3 iron atom is in a ferryl (Fe4+ = O2-) configuration, and heme a and CuB are oxidized while CuA is reduced. A Helix-X segment is poised in an open conformational state; the heme a farnesyl sidechain is H-bonded to S382, and loop-I-II adopts a distinct structure. These data offer insights into the mechanism by which the oxygen chemistry is coupled to unidirectional proton translocation.
    Keywords:  X-ray free electron laser; bioenergetics; catalytic intermediates; complex IV; crystallography