IMR Press / FBL / Volume 22 / Issue 9 / DOI: 10.2741/4550

Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.

Open Access Review

Photosystem II and terminal respiratory oxidases: molecular machines operating in opposite directions

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1 Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russian Federation

Academic Editor: Mahir D. Mamedov

Front. Biosci. (Landmark Ed) 2017, 22(9), 1379–1426; https://doi.org/10.2741/4550
Published: 1 March 2017
Abstract

In the thylakoid membrane of green plants, cyanobacteria and algae, photosystem II (PSII) uses light energy to split water and generate molecular oxygen. In the opposite process of the biochemical transformation of dioxygen, in heterotrophs, the terminal respiratory oxidases (TRO) are at the end of the respiratory chain in mitochondria and in plasma membrane of many aerobic bacteria reducing dioxygen back to water. Despite the different sources of free energy (light or oxidation of the substrates), energy conversion by these enzymes is based on the spatial organization of enzymatic reactions in which the conversion of water to dioxygen (and vice versa) involves the transfer of protons and electrons in opposite directions across the membrane, which is accompanied by generation of proton-motive force. Similar and distinctive features in structure and function of these important energy-converting molecular machines are described. Information about many fascinating parallels between the mechanisms of TRO and PSII could be used in the artificial light-driven water-splitting process and elucidation of energy conversion mechanism in protein pumps.

Keywords
Photosystem
Cytochrome
Oxidase
Protons
Membrane potential
Channels
Electrogenic
Voltage
Electron injection
Review
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