The plastocyanin binding domain of photosystem I
The plastocyanin binding domain of photosystem I
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DOI：
10.1002/j.1460-2075.1996.tb01028.x
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发表时间：
1996-12-02
期刊：
影响因子：
11.4
通讯作者：
Haehnel, W
中科院分区：
文献类型：
--
作者：
Hippler, M;Reichert, J;Haehnel, W
研究了叶绿体蓝素和光系统I之间的分子识别，光系统I和叶绿体蛋白可以被交联到一个活跃的电子转移复合体上，免疫印迹和蛋白质水解肽的质谱分析表明，植物叶绿体蛋白中保守的两个负的斑块与光系统I的PSAF亚基N端附近的区域的赖氨酸残基交联，分别通过定点突变D42N/E43Q/D44N/E45Q和E59Q/E60Q/D61N将这些负的斑块转化为不带电荷的斑块，表明第一个斑块是与光系统I的电子转移复合体中的静电相互作用所必需的，第二个斑块是降低氧化还原电位的。在蓝藻中没有发现，预测折叠成两个两亲性的α-螺旋，相互作用的N-末端螺旋排列在一侧的六个赖氨酸可能引导快速的一维扩散并在附着位置提供静电吸引，除了在光系统I的反应中心电子转移到P700的疏水相互作用外，这种两步相互作用很可能使植物中的电子传递速率比蓝藻提高两个数量级以上，我们的数据解决了关于PSAF功能的争议。
The molecular recognition between plastocyanin and photosystem I was studied, Photosystem I and plastocyanin can be cross-linked to an active electron transfer complex, Immunoblots and mass spectrometric analysis of proteolytic peptides indicate that the two negative patches conserved in plant plastocyanins are cross-linked with lysine residues of a domain near the N-terminus of the PsaF subunit of photosystem I, Conversion of these negative to uncharged patches of plastocyanin by site-directed mutation D42N/E43Q/D44N/E45Q and E59Q/E60Q/D61N respectively, reveals the first patch to be essential for the electrostatic interaction in the electron transfer complex with photosystem I and the second one to lower the redox potential, The domain in PsaF, not found in cyanobacteria, is predicted to fold into two amphipathic alpha-helices, The interacting N-terminal helix lines up six lysines on one side which may guide a fast one-dimensional diffusion of plastocyanin and provide the electrostatic attraction at the attachment site, in addition to the hydrophobic interaction in the area where the electron is transferred to P700 in the reaction center of photosystem I, This two-step interaction is likely to increase the electron transfer rate by more than two orders of magnitude in plants as compared with cyanobacteria, Our data resolve the controversy about the function of PsaF.