The cytochrome b6f complex at the crossroad of photosynthetic electron transport pathways

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Abstract

Regulation of photosynthetic electron transport at the level of the cytochrome b6f complex provides efficient performance of the chloroplast electron transport chain (ETC). In this review, after brief overview of the structural organization of the chloroplast ETC, the consideration of the problem of electron transport control is focused on the plastoquinone (PQ) turnover and its interaction with the b6f complex. The data available show that the rates of plastoquinol (PQH2) formation in PSII and its diffusion to the b6f complex do not limit the overall rate of electron transfer between photosystem II (PSII) and photosystem I (PSI). Analysis of experimental and theoretical data demonstrates that the rate-limiting step in the intersystem chain of electron transport is determined by PQH2 oxidation at the Qo-site of the b6f complex, which is accompanied by the proton release into the thylakoid lumen. The acidification of the lumen causes deceleration of PQH2 oxidation, thus impeding the intersystem electron transport. Two other mechanisms of regulation of the intersystem electron transport have been considered: (i) "state transitions" associated with the light-induced redistribution of solar energy between PSI and PSII, and (ii) redistribution of electron fluxes between alternative pathways (noncyclic electron transport and cyclic electron flow around PSI).

Original languageEnglish
Pages (from-to)163-183
Number of pages21
JournalPlant Physiology and Biochemistry
Volume81
DOIs
Publication statusPublished - 2014
Externally publishedYes

Fingerprint

Cytochrome b6f Complex
cytochromes
Electron Transport
electron transfer
photosystem I
electron transport chain
Photosystem I Protein Complex
photosystem II
Photosystem II Protein Complex
Electrons
Chloroplasts
chloroplasts
electrons
oxidation
solar energy
Plastoquinone
Solar Energy
thylakoids
protons
acidification

Keywords

  • Chloroplasts
  • Electron transport control
  • Photosynthesis
  • Plastoquinone

ASJC Scopus subject areas

  • Plant Science
  • Genetics
  • Physiology
  • Medicine(all)

Cite this

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