Thylakoid potassium channel is required for efficient photosynthesis in cyanobacteria

Vanessa Checchetto, Anna Segalla, Guillaume Allorent, Nicoletta La Rocca, Luigi Leanza, Giorgio Mario Giacometti, Nobuyuki Uozumi, Giovanni Finazzi, Elisabetta Bergantino, Ildikò Szabò

Research output: Contribution to journalArticlepeer-review

50 Citations (Scopus)


A potassium channel (SynK) of the cyanobacterium Synechocystis sp. PCC 6803, a photoheterotrophic model organism for the study of photosynthesis, has been recently identified and demonstrated to function as a potassium selective channel when expressed in a heterologous system and to be located predominantly to the thylakoid membrane in cyanobacteria. To study its physiological role, a SynK-less knockout mutant was generated and characterized. Fluorimetric experiments indicated that SynK-less cyanobacteria cannot build up a proton gradient as efficiently as WT organisms, suggesting that SynK might be involved in the regulation of the electric component of the proton motive force. Accordingly, measurements of flash-induced cytochrome b6f turnover and respiration pointed to a reduced generation of ΔpH and to an altered linear electron transport in mutant cells. The lack of the channel did not cause an altered membrane organization, but decreased growth and modified the photosystem II/photosystem I ratio at high light intensities because of enhanced photosensitivity. These data shed light on the function of a prokaryotic potassium channel and reports evidence, by means of a genetic approach, on the requirement of a thylakoid ion channel for optimal photosynthesis.

Original languageEnglish
Pages (from-to)11043-11048
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number27
Publication statusPublished - 2012 Jul 3


  • Bioenergetics
  • Ion flux
  • Membrane potential


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