IBR   13079
INSTITUTO DE BIOLOGIA MOLECULAR Y CELULAR DE ROSARIO
Unidad Ejecutora - UE
artículos
Título:
Redox-state sensing by hydrogen bonds in the CuA center of cytochrome c oxidase
Autor/es:
ABRIATA LA; A. J. VILA
Revista:
JOURNAL OF INORGANIC BIOCHEMISTRY
Editorial:
ELSEVIER SCIENCE INC
Referencias:
Lugar: Amsterdam; Año: 2014 vol. 132 p. 18 - 20
ISSN:
0162-0134
Resumen:
Cytochrome c oxidases (CcO) couple electron transfer to active proton
translocation through a gated mechanism that minimizes energy losses by
preventing protons from flowing backwards or leaking. Such a complex
mechanism requires that information about the redox and protonation
states of the different centers be transmitted between different parts
of the oxidase. Here we report a network of residues located around the
electron entry point of CcO, the CuA site in subunit II, that experience
collective pH equilibria around neutral pH. This network starts at the
occluded side of the CuA site and extends to the interface between
subunits I and II of the CcO, where the proton exit is located and
through which electrons flow into subunit I. One of the residues in this
network is directly involved in a hydrogen bond to one of the CuA
ligands, whose strength is highly sensitive to the redox state of the
metal center. We propose that this interaction mediates the transmission
of redox changes from ET centers to other functional regions of the
oxidase, and possibly also in other similar machineries, as part of
their gating and regulatory mechanisms.