The location of plastocyanin in vascular plant photosystem I.
We have studied the binding sites of the electron donor and acceptor proteins of vascular plant photosystem I by electron microscopy/crystallography. Previously, we identified the binding site for the electron acceptor (ferredoxin). In this paper we complete these studies with the characterization of the electron donor (plastocyanin) binding site. After cross-linking, plastocyanin is detected using Fourier difference analysis of two dimensionally ordered arrays of photosystem I located at the periphery of chloroplast grana. Plastocyanin binds in a small cavity on the lumenal surface of photosystem I, close to the center and with a slight bias toward the PsaL subunit of the complex. The recent release of the full coordinates for the cyanobacterial photosystem I reaction center has allowed a detailed comparison between the structures of the eukaryotic and prokaryotic systems. This reveals a very close homology, which is particularly striking for the lumenal side of photosystem I.
Ruffle
Stuart V
SV
School of Biological Sciences, University of Exeter, United Kingdom.
Mustafa
Aziz O
AO
Kitmitto
Ashraf
A
Holzenburg
Andreas
A
Ford
Robert C
RC
D001665:Binding Sites; D005288:Ferredoxins / Q000378:metabolism; D008854:Microscopy, Electron; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism* / Q000648:ultrastructure; D045331:Photosystem I Protein Complex; D010970:Plastocyanin / Q000378:metabolism*; D018724:Spinacia oleracea / Q000378:metabolism*
D005288:Ferredoxins; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D010970:Plastocyanin