A systematic survey of conserved histidines in the core subunits of Photosystem I by site-directed mutagenesis reveals the likely axial ligands of P700

Kevin Edward Redding, Fraser MacMillan, Winfried Leibl, Klaus Brettel, Jonathan Hanley, A. William Rutherford, Jacques Breton, Jean David Rochaix

Research output: Contribution to journalArticle

76 Citations (Scopus)

Abstract

The Photosystem I complex catalyses the transfer of an electron from lumenal plastocyanin to stromal ferredoxin, using the energy of an absorbed photon. The initial photochemical event is the transfer of an electron from the excited state of P700, a pair of chlorophylls, to a monomer chlorophyll serving as the primary electron acceptor. We have performed a systematic survey of conserved histidines in the last six transmembrane segments of the related polytopic membrane proteins PsaA and PsaB in the green alga Chlamydomonas reinhardtii. These histidines, which are present in analogous positions in both proteins, were changed to glutamine or leucine by site-directed mutagenesis. Double mutants in which both histidines had been changed to glutamine were screened for changes in the characteristics of P700 using electron paramagnetic resonance, Fourier transform infrared and visible spectroscopy. Only mutations in the histidines of helix 10 (PsaA-His676 and PsaB-His656) resulted in changes in spectroscopic properties of P700, leading us to conclude that these histidines are most likely the axial ligands to the P700 chlorophylls.

Original languageEnglish
Pages (from-to)50-60
Number of pages11
JournalEMBO Journal
Volume17
Issue number1
DOIs
Publication statusPublished - Jan 2 1998

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Photosystem I Protein Complex
Mutagenesis
Site-Directed Mutagenesis
Histidine
Ligands
Chlorophyll
Electrons
Glutamine
Plastocyanin
Chlamydomonas reinhardtii
Ferredoxins
Chlorophyta
Electron Spin Resonance Spectroscopy
Fourier Transform Infrared Spectroscopy
Algae
Photons
Excited states
Leucine
Paramagnetic resonance
Fourier transforms

Keywords

  • Chlamydomonas reinhardtii
  • EPR
  • FTIR
  • Photosystem I
  • Site-directed mutagenesis

ASJC Scopus subject areas

  • Genetics
  • Cell Biology

Cite this

A systematic survey of conserved histidines in the core subunits of Photosystem I by site-directed mutagenesis reveals the likely axial ligands of P700. / Redding, Kevin Edward; MacMillan, Fraser; Leibl, Winfried; Brettel, Klaus; Hanley, Jonathan; Rutherford, A. William; Breton, Jacques; Rochaix, Jean David.

In: EMBO Journal, Vol. 17, No. 1, 02.01.1998, p. 50-60.

Research output: Contribution to journalArticle

Redding, Kevin Edward ; MacMillan, Fraser ; Leibl, Winfried ; Brettel, Klaus ; Hanley, Jonathan ; Rutherford, A. William ; Breton, Jacques ; Rochaix, Jean David. / A systematic survey of conserved histidines in the core subunits of Photosystem I by site-directed mutagenesis reveals the likely axial ligands of P700. In: EMBO Journal. 1998 ; Vol. 17, No. 1. pp. 50-60.
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