期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2010
卷号：107
期号：45
页码：19260-19265
DOI：10.1073/pnas.1009124107
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Ferredoxin:NADPH oxidoreductase (FNR) is a key enzyme of photosynthetic electron transport required for generation of reduction equivalents. Recently, two proteins were found to be involved in membrane-anchoring of FNR by specific interaction via a conserved Ser/Pro-rich motif: Tic62 and Trol. Our crystallographic study reveals that the FNR-binding motif, which forms a polyproline type II helix, induces self-assembly of two FNR monomers into a back-to-back dimer. Because binding occurs opposite to the FNR active sites, its activity is not affected by the interaction. Surface plasmon resonance analyses disclose a high affinity of FNR to the binding motif, which is strongly increased under acidic conditions. The pH of the chloroplast stroma changes dependent on the light conditions from neutral to slightly acidic in complete darkness or to alkaline at saturating light conditions. Recruiting of FNR to the thylakoids could therefore represent a regulatory mechanism to adapt FNR availability/activity to photosynthetic electron flow.
