Plastocyanin-cytochrome f interactions:: The influence of hydrophobic patch mutations studied by NMR spectroscopy
Plastocyanin-cytochrome f interactions:: The influence of hydrophobic patch mutations studied by NMR spectroscopy
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DOI：
10.1021/bi026349b
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发表时间：
2002-12-31
期刊：
影响因子：
2.9
通讯作者：
Ubbink, M
中科院分区：
文献类型：
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作者：
Crowley, PB;Vintonenko, N;Ubbink, M
利用核磁共振（NMR）技术研究了原绿丝菌（Prochlorothrix hollandica）的质体蓝素与层片席藻（Phormidium laminosum）的细胞色素f之间的瞬时复合物形成。在10 mM离子强度下由NMR滴定得到的结合曲线显示了1：1的化学计量比和6（+/-2）x 10（3）M-1的复合物形成的结合常数，比来自Ph. laminosum的生理质体蓝素-细胞色素f复合物的结合常数大I个数量级。化学位移微扰映射表明，疏水补丁的质体蓝素参与复杂的界面。当不寻常的疏水补丁残基的P. hollandica质体蓝素恢复到保守的残基中发现的大多数其他质体蓝素（Y12 G/P14 L），与细胞色素f的相互作用的结合常数不受影响。然而，化学位移扰动图是相当不同的，平均扰动的大小减少了40%。与生理复合物相反，野生型和双突变体质体蓝素与细胞色素f的复合物对离子强度敏感。这些研究结果的瞬态复杂的形成机制的可能影响进行了讨论。
Transient complex formation between plastocyanin from Prochlorothrix hollandica and cytochrome f from Phormidium laminosum was investigated using nuclear magnetic resonance (NMR) spectroscopy. Binding curves derived from NMR titrations at 10 mM ionic strength reveal a 1:1 stoichiometry and a binding constant of 6 (+/-2) x 10(3) M-1 for complex formation, I order of magnitude larger than that for the physiological plastocyanin-cytochrome f complex from Ph. laminosum. Chemical-shift perturbation mapping indicates that the hydrophobic patch of plastocyanin is involved in the complex interface. When the unusual hydrophobic patch residues of P. hollandica plastocyanin were reverted to the conserved residues found in most other plastocyanins (Y12G/P14L), the binding constant for the interaction with cytochrome f was unaffected. However, the chemical shift perturbation map was considerably different, and the size of the average perturbation decreased by 40%. The complexes of both the wild-type and double mutant plastocyanin with cytochrome f were sensitive to ionic strength, contrary to the physiological complex. The possible implications of these findings for the mechanism of transient complex formation are discussed.