Species-dependent alteration of electron transfer in the early stages of charge stabilization in Photosystem i

Michael D. McConnell, Junlei Sun, Reza Siavashi, Andrew Webber, Kevin Edward Redding, John H. Golbeck, Art Van Der Est

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Electron transfer (ET) in Photosystem I (PS I) is bidirectional, occurring in two pseudosymmetric branches of cofactors. The relative use of two branches in the green alga Chlamydomonas reinhardtii and the cyanobacterium Synechocystis sp. PCC 6803 has been studied by changing the Met axial ligands of the chlorophyll a acceptor molecules, A0A and A0B, to His. The nature of the effect on the ET is found to be species dependent. In C. reinhardtii, transient absorption and transient EPR data show that in the M688HPsaA variant, forward ET from A0A to the quinone, A1A, is blocked in 100% of the PS I complexes. In contrast, in Synechocystis sp. PCC 6803, forward ET from A0A to A1A is blocked in only 50% of the PS I complexes, but in those PS I complexes in which electrons reach A1A, further transfer to the iron-sulfur cluster FX is blocked. Similar species differences are found for the corresponding B-branch variants. One possible explanation of this behavior is that it is the result of two conformers in which an H-bond between the His side chain and the O1 carbonyl group of A1 is either present or absent. The spectroscopic data suggest that the two conformers are present in nearly equal amounts in the Synechocystis sp. PCC 6803 variants, while only the conformer without the H-bond is present in the same variants of C. reinhardtii.

Original languageEnglish
Pages (from-to)429-440
Number of pages12
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume1847
Issue number4-5
DOIs
Publication statusPublished - 2015

Fingerprint

Photosystem I Protein Complex
Synechocystis
Chlamydomonas reinhardtii
Stabilization
Electrons
Chlorophyta
Cyanobacteria
Algae
Sulfur
Paramagnetic resonance
Iron
Ligands
Molecules

Keywords

  • A<inf>0</inf>
  • Electron transfer
  • Photosynthesis
  • Photosystem I
  • Phylloquinone

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Cell Biology
  • Medicine(all)

Cite this

Species-dependent alteration of electron transfer in the early stages of charge stabilization in Photosystem i. / McConnell, Michael D.; Sun, Junlei; Siavashi, Reza; Webber, Andrew; Redding, Kevin Edward; Golbeck, John H.; Van Der Est, Art.

In: Biochimica et Biophysica Acta - Bioenergetics, Vol. 1847, No. 4-5, 2015, p. 429-440.

Research output: Contribution to journalArticle

McConnell, Michael D. ; Sun, Junlei ; Siavashi, Reza ; Webber, Andrew ; Redding, Kevin Edward ; Golbeck, John H. ; Van Der Est, Art. / Species-dependent alteration of electron transfer in the early stages of charge stabilization in Photosystem i. In: Biochimica et Biophysica Acta - Bioenergetics. 2015 ; Vol. 1847, No. 4-5. pp. 429-440.
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