Paramagnetic NMR analysis of the seven-iron ferredoxin from the hyperthermoacidophilic archaeon Desulfurolobus ambivalens reveals structural similarity to other dicluster ferredoxins
Paramagnetic NMR analysis of the seven-iron ferredoxin from the hyperthermoacidophilic archaeon Desulfurolobus ambivalens reveals structural similarity to other dicluster ferredoxins
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DOI：
10.1111/j.1432-1033.1996.00092.x
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发表时间：
1996-02-15
期刊：
影响因子：
--
通讯作者：
Teixeira, M
中科院分区：
文献类型：
--
作者：
Bentrop, D;Bertini, I;Teixeira, M
利用一维和二维H-1-NMR研究了极端嗜热古菌Desulfuroobus ambivalens中7-Fe铁氧还蛋白的氧化态和连二亚硫酸盐还原态。铝铁原子的三铁和四铁集群绑定到半胱氨酸残基的超精细位移共振的特点。这些共振的模式与文献中先前描述的三铁、四铁和八铁氧化还原蛋白的模式相似，但四铁簇的移位模式与其他七铁蛋白不同。第二组超精细位移共振清楚地表明了样本的不均匀性，这可能涉及到四伊朗星系团。两个不同半胱氨酸残基间NOE的观测证明了D. ambivalens铁氧还蛋白，因此表明与其他二簇铁氧还蛋白的结构同源性。此外，该特征对于超精细位移共振的序列特异性分配是至关重要的。计算了半胱氨酸残基配位四铁簇合物的C α-C β-S-Fe二面角，讨论了三铁簇合物的电子结构。
The seven-iron ferredoxin from the hyperthermophilic archaeon Desulfurolobus ambivalens has been investigated by one-dimensional and two-dimensional H-1-NMR in its oxidized and dithionite-reduced states. Al iron atoms of both the three-iron and the four-iron cluster are bound to cysteine residues whose hyperfine shifted resonances were characterized. The pattern of these resonances is similar to those from three-iron, four-iron and eight-iron ferredoxins previously described in the literature, but the four-iron cluster has a shift pattern different from that in other seven-iron proteins. A second set of hyperfine-shifted resonances clearly indicates sample heterogeneity, which possibly involves the four-iran cluster. The observation of interresidue NOEs between two different cysteine residues proves the existence of close spatial proximity of the two dusters in D. ambivalens ferredoxin and therefore indicates structural homology to other dicluster ferredoxins. Moreover, this feature is crucial for the sequence-specific assignment of the hyperfine-shifted resonances. The C alpha-C beta-S-Fe dihedral angles of the cysteine residues coordinating the four-iron cluster could be estimated, and the electronic structure of the three-iron cluster is discussed.