Photosystem I, an improved model of the stromal subunits PsaC, PsaD, and PsaE

Olaf Klukas, Wolf Dieter Schubert, Patrick Jordan, Norbert Krauß, Petra Fromme, Horst Tobias Witt, Wolfram Saenger

Research output: Contribution to journalArticle

78 Scopus citations

Abstract

An improved electron density map of photosystem I (PSI) calculated at 4- Å resolution yields a more detailed structural model of the stromal subunits PsaC, PsaD, and PsaE than previously reported. The NMR structure of the subunit PsaE of PSI from Synechococcus sp. PCC7002 (Falzone, C. J., Kao, Y.- H., Zhao, J., Bryant, D. A., and Lecomte, J. T. J. (1994) Biochemistry 33, 6052-6062) has been used as a model to interpret the region of the electron density map corresponding to this subunit. The spatial orientation with respect to other subunits is described as well as the possible interactions between the stromal subunits. A first model of PsaD consisting of a four- stranded β-sheet and an α-helix is suggested, indicating that this subunit partly shields PsaC from the stromal side. In addition to the improvements on the stromal subunits, the structural model of the membrane-integral region of PSI is also extended. The current electron density map allows the identification of the N and C termini of the subunits PsaA and PsaB. The 11- transmembrane α-helices of these subunits can now be assigned uniquely to the hydrophobic segments identified by hydrophobicity analyses.

Original languageEnglish (US)
Pages (from-to)7351-7360
Number of pages10
JournalJournal of Biological Chemistry
Volume274
Issue number11
DOIs
StatePublished - Mar 12 1999
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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    Klukas, O., Schubert, W. D., Jordan, P., Krauß, N., Fromme, P., Witt, H. T., & Saenger, W. (1999). Photosystem I, an improved model of the stromal subunits PsaC, PsaD, and PsaE. Journal of Biological Chemistry, 274(11), 7351-7360. https://doi.org/10.1074/jbc.274.11.7351