Mapping the interactions between flavodoxin and its physiological partners flavodoxin reductase and cobalamin-dependent methionine synthase
Mapping the interactions between flavodoxin and its physiological partners flavodoxin reductase and cobalamin-dependent methionine synthase
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DOI：
10.1073/pnas.171168898
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发表时间：
2001-08-14
影响因子：
11.1
通讯作者：
Matthews, RG
中科院分区：
文献类型：
--
作者：
Hall, DA;Kooi, CWV;Matthews, RG
黄毒毒素是含有假体基黄素单核苷酸的电子转移蛋白。在大肠杆菌中，黄氧还蛋白被含有fad的蛋白NADPH还原：铁氧化还蛋白（黄氧还蛋白）氧化还原酶；黄毒毒素在厌氧核糖核苷酸还原酶、生物素合成酶、丙酮酸甲酸裂解酶和钴胺依赖的蛋氨酸合成酶的还原激活中充当电子供体。此外，与黄氧还蛋白同源的结构域是多结构域黄素蛋白细胞色素P450还原酶、一氧化氮合酶和蛋氨酸合酶还原酶的组成部分。虽然这些蛋白质和结构域的三维结构是已知的，但它们相互作用的结构方面所知甚少。我们通过使用核磁共振化学位移映射来识别黄伏氧素上结合黄伏氧素还原酶和蛋氨酸合成酶的表面来解决这个问题。我们发现这些生理伴侣结合到黄氧还蛋白上独特的重叠位点，阻止了三元复合物的形成。我们推断细胞色素P450还原酶家族的黄毒毒素样结构域与它们的供电子和接受电子的伙伴形成互斥的配合物，这些配合物需要改变构象才能相互转化。
Flavodoxins are electron-transfer proteins that contain the prosthetic group flavin mononucleotide. In Escherichia coli, flavodoxin is reduced by the FAD-containing protein NADPH:ferredoxin (flavodoxin) oxidoreductase; flavodoxins serve as electron donors in the reductive activation of anaerobic ribonucleotide reductase, biotin synthase, pyruvate formate lyase, and cobalamin-dependent methionine synthase. In addition, domains homologous to flavodoxin are components of the multidomain flavoproteins cytochrome P450 reductase, nitric oxide synthase, and methionine synthase reductase. Although three-dimensional structures are known for many of these proteins and domains, very little is known about the structural aspects of their interactions. We address this issue by using NMR chemical shift mapping to identify the surfaces on flavodoxin that bind flavodoxin reductase and methionine synthase. We find that these physiological partners bind to unique overlapping sites on flavodoxin, precluding the formation of ternary complexes. We infer that the flavodoxin-like domains of the cytochrome P450 reductase family form mutually exclusive complexes with their electron-donating and -accepting partners, complexes that require conformational changes for interconversion.