Reconstitution of the photosystem I complex from the P700 and Fx‐containing reaction center core protein and the FA/FB polypeptide

FEBS Letters

Parrett, Kevin¹  Ikegami, Isamu¹  Mehari, Tetemke¹  Golbeck, John H.¹ 

[1] Department of Chemistry, Portland State University, Portland, OR 97207, USA

关键词: Photosystem I;    Reaction center;    Reconstitution;    Iron-sulfur center;    Core protein;    FA/FB protein;    PS;    photosystem;    Chl;    chlorophyll;    DCPIP;    2;    6-dichlorophenolindophenol;    Photosystem I complex: multiprotein reaction center isolated with Triton X-100;    containing P700 and acceptors A0;    A1;    FX;    FB and FA. Photosystem I core protein: reaction center heterodimer of psaA and psaB isolated from the photosystem I complex with chaotropes;    containing P700 and acceptors A0;    A1 and FX. FA/FB polypeptide: 8.9 kDa polypeptide isolated by acetone precipitation;    containing iron-sulfur centers FA and FB. Reconstituted photosystem I complex: photosystem I core protein containing rebound FA/FB polypeptide;   

DOI  :  10.1016/0014-5793(88)80331-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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_BI-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.

【 授权许可】

Unknown