Electrostatic influence of PsaC protein binding to the PsaA/PsaB heterodimer in photosystem I

Hiroshi Ishikita, Dietmar Stehlik, John H. Golbeck, Ernst Walter Knapp

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The absence of the PsaC subunit in the photosystem I (PSI) complex (native PSI complex) by mutagenesis or chemical manipulation yields a PSI core (P700-FX core) that also lacks subunits PsaD and PsaE and the two iron-sulfur clusters FA and FB, which constitute an integral part of PsaC. In this P700-FX core, the redox potentials (Em) of the two quinones A1A/B and the iron-sulfur cluster FX as well as the corresponding protonation patterns are investigated by evaluating the electrostatic energies from the solution of the linearized Poisson-Boltzmann equation. The B-side specific Asp-B558 changes its protonation state significantly upon isolating the P700-FX core, being mainly protonated in the native PSI complex but ionized in the P700-FX core. In the P700-FX core, Em(A1A/B) remains practically unchanged, whereas Em(FX) is upshifted by 42 mV. With these calculated Em values, the electron transfer rate from A1 to FX in the P700-FX core is estimated to be slightly faster on the A1A side than that of the wild type, which is consistent with kinetic measurements.

Original languageEnglish (US)
Pages (from-to)1081-1089
Number of pages9
JournalBiophysical journal
Volume90
Issue number3
DOIs
StatePublished - Feb 2006

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Photosystem I Protein Complex
Static Electricity
Protein Binding
Sulfur
Iron
Quinones
Mutagenesis
Oxidation-Reduction
Electrons
psaB subunit photosystem I

All Science Journal Classification (ASJC) codes

  • Biophysics

Cite this

Ishikita, Hiroshi ; Stehlik, Dietmar ; Golbeck, John H. ; Knapp, Ernst Walter. / Electrostatic influence of PsaC protein binding to the PsaA/PsaB heterodimer in photosystem I. In: Biophysical journal. 2006 ; Vol. 90, No. 3. pp. 1081-1089.
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Electrostatic influence of PsaC protein binding to the PsaA/PsaB heterodimer in photosystem I. / Ishikita, Hiroshi; Stehlik, Dietmar; Golbeck, John H.; Knapp, Ernst Walter.

In: Biophysical journal, Vol. 90, No. 3, 02.2006, p. 1081-1089.

Research output: Contribution to journalArticle

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