Ferredoxin:NADPH oxidoreductase is recruited to thylakoids by binding to a polyproline type II helix in a pH-dependent manner
Ferredoxin:NADPH oxidoreductase is recruited to thylakoids by binding to a polyproline type II helix in a pH-dependent manner
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DOI：
10.1073/pnas.1009124107
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发表时间：
2010-11-09
影响因子：
11.1
通讯作者：
Boelter, Bettina
中科院分区：
文献类型：
--
作者：
Alte, Ferdinand;Stengel, Anna;Boelter, Bettina
铁氧还蛋白：NADPH氧化还原酶（FNR）是光合作用电子传递过程中产生还原当量的关键酶。最近，发现两种蛋白质通过保守的富含Ser/Pro的基序通过特异性相互作用参与FNR的膜锚定：Tic 62和Trol。我们的晶体学研究表明，FNR结合基序，形成一个聚脯氨酸II型螺旋，诱导两个FNR单体自组装成一个背靠背的二聚体。由于结合发生在FNR活性位点的对面，因此其活性不受相互作用的影响。表面等离子体共振分析揭示了FNR对结合基序的高亲和力，其在酸性条件下强烈增加。叶绿体基质的pH值的变化依赖于光条件从中性到微酸性在完全黑暗或碱性在饱和光条件。因此，类囊体的FNR招募可能代表了一种调节机制，以适应FNR的可用性/活性光合电子流。
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.