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Reconstitution of Barley Photosystem I with Modified PSI-C Allows Identification of Domains Interacting with PSI-D and PSI-A/B
The Journal of Biological Chemistry (1996)
  • Helle Naver, Royal Veterinary and Agricultural University
  • M. Paul Scott, University of Nebraska - Lincoln
  • John H. Golbeck, University of Nebraska - Lincoln
  • Birger L. Møller, Royal Veterinary and Agricultural University
  • Henrik V. Scheller, Royal Veterinary and Agricultural University
Abstract
The PSI-C subunit of photosystem I shows similarity to soluble 2[4Fe-4S] ferredoxins. Alignment analysis clearly shows that PSI-C contains an 8-residue internal loop and a 15-residue C-terminal extension that are absent in the ferredoxins. The remaining residues in PSI-C are likely to be folded in a way similar to the soluble 2[4Fe-4S] ferredoxins. Two modified PSI-C subunits lacking either the 8-residue loop or 10 residues of the C terminus were expressed in Escherichia coli and used to reconstitute a barley P700-F core prepared to specifically lack PSI-C, PSI-D, and PSI-E. As shown by EPR spectroscopy, the modified proteins carry two [4Fe-4S] clusters with characteristics similar to those of native PSI-C. Western blot analysis of the reconstituted photosystem I complexes showed that the modified PSI-C proteins bind to the P700-F core. Flash photolysis revealed that in photosystem I complexes reconstituted in the presence of PSI-D with the C-terminally deleted PSI-C, the F/Fback-reaction was less efficiently restored than with wild-type PSI-C. The loop-deleted PSI-C was even less efficient. We attribute these differences to altered binding properties of the modified proteins. Comparison of reconstitutions performed in the presence and absence of PSI-D shows that the loop-deleted PSI-C is unable to bind without PSI-D, whereas the C-terminally deleted PSI-C binds only weakly with PSI-D. These results imply that the internal loop of PSI-C interacts with the PSI-A/B heterodimer and that the C terminus of PSI-C interacts with PSI-D.
Publication Date
April 12, 1996
DOI
10.1074/jbc.271.15.8996
Publisher Statement
This research was originally published in Journal of Biological Chemistry. Naver, Helle, M. Paul Scott, John H. Golbeck, Birger L. Møller, and Henrik V. Scheller. "Reconstitution of barley photosystem I with modified PSI-C allows identification of domains interacting with PSI-D and PSI-A/B." Journal of Biological Chemistry (1996) 271: 8996-9001. © the American Society for Biochemistry and Molecular Biology.
Citation Information
Helle Naver, M. Paul Scott, John H. Golbeck, Birger L. Møller, et al.. "Reconstitution of Barley Photosystem I with Modified PSI-C Allows Identification of Domains Interacting with PSI-D and PSI-A/B" The Journal of Biological Chemistry Vol. 271 Iss. 15 (1996) p. 8996 - 9001
Available at: http://works.bepress.com/paul-scott/49/