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Reconstitution of the photosystem I complex from the P700 and F x ‐containing reaction center core protein and the F A /F B polypeptide
Author(s) -
Golbeck John H.,
Mehari Tetemke,
Parrett Kevin,
Ikegami Isamu
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)80331-4
Subject(s) - p700 , photosystem i , photosynthetic reaction centre , chemistry , crystallography , acceptor , electron acceptor , spinach , stereochemistry , electron transfer , photosystem ii , photochemistry , photosynthesis , physics , biochemistry , condensed matter physics
Complete restoration of electron flow from P700 to F A /F B was achieved by incubating a P700 and F x ‐containing photosystem (PS) I core protein from Synechococcus sp. 6301 with the 8.9 kDa, F A /F B polypeptide from spinach. The ESR spectrum of the reconstituted PS I complex shows nearly equal photochemical reduction of F A and F B when frozen in darkness and illuminated at 16 K. When illuminated during freezing, both F A and F B are quantitatively reduced and the spectrum is nearly indistinguishable from F A and F B in the control PS I complex. In the reconstituted PS I complex F x is photochemically reduced only in the presence of F − A and F − B , and the high‐field resonance appears indistinguishable from F x in the control PS I complex. Optical flash photolysis after extensive washing confirms the complete restoration of the P700 + [F A /F B I‐back‐reaction, indicating quantitative rebinding of the 8.9 kDA polypeptide. This procedure represents the first reconstitution of the PS I complex from a purified PS I core protein and an isolated 8.9 kDa, F A /F B polypeptide, and makes possible independent manipulation of the two subunits that carry the entire electron acceptor system of PS I.