The cyanobacterial cytochrome b6f subunit PetP adopts an SH3 fold in solution.
The cyanobacterial cytochrome b6f subunit PetP adopts an SH3 fold in solution.
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蓝藻细胞色素 b6f 亚基 PetP 在溶液中采用 SH3 折叠。
DOI：
10.1016/j.bbabio.2016.03.023
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Ikegami T.
中科院分区：
文献类型：
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作者：
Veit S;Nagadoi A;Roegner M;Rexroth S;Stoll R;Ikegami T.
PetP是蓝藻和红藻细胞色素b6f复合体(B6f)的外周亚基。尽管它不直接参与电子传递反应，但它结合在这个膜蛋白复合体的细胞质表面，在那里它极大地影响了线性光合作用电子流的效率。尽管b6fcore复合体的晶体结构，关于瞬时调节因子b6f亚基的结构信息仍然缺乏。在这里，我们介绍了由溶液核磁共振确定的第一个原子分辨率的PetP结构。该蛋白采用SH3折叠，这是真核生物中常见的蛋白质基序，但在原核生物中相对罕见。PetP的结构使得通过保守作图识别b6f结合的潜在相互作用位点成为可能。相互作用面主要由两个大的环区和一个短的310螺旋组成，由异核稳态的{1H}-15N NOE和无规卷曲指数参数表明，相互作用的柔性也增加了。这个潜在的b6f结合位点的性质与在真核细胞SH3结构域中高度保守的典型多肽结合位点有很大不同。有趣的是，光合作用电子传递链中的另外三个蛋白质与PetP具有相同的SH3序列：光合NADH脱氢酶类复合体(NDH-1)的NdHs、光系统1的PsaE和铁氧还蛋白-硫氧还蛋白还原酶的亚基α与PetP相似，对光合作用的电子传递有很大的影响。最后，给出了一个模型来说明SH3结构域如何调节蓝藻的光合作用电子传递过程。
PetP is a peripheral subunit of the cytochromeb6fcomplex (b6f) present in both, cyanobacteria and red algae. It is bound to the cytoplasmic surface of this membrane protein complex where it greatly affects the efficiency of the linear photosynthetic electron flow although it is not directly involved in the electron transfer reactions.Despite the crystal structures of theb6fcore complex, structural information for the transient regulatoryb6fsubunits is still missing. Here we present the first structure of PetP at atomic resolution as determined by solution NMR. The protein adopts an SH3 fold, which is a common protein motif in eukaryotes but comparatively rare in prokaryotes. The structure of PetP enabled the identification of the potential interaction site forb6fbinding by conservation mapping. The interaction surface is mainly formed by two large loop regions and one short 310helix which also exhibit an increased flexibility as indicated by heteronuclear steady-state {1H}–15N NOE and random coil index parameters. The properties of this potentialb6fbinding site greatly differ from the canonical peptide binding site which is highly conserved in eukaryotic SH3 domains. Interestingly, three other proteins of the photosynthetic electron transport chain share this SH3 fold with PetP: NdhS of the photosynthetic NADH dehydrogenase-like complex (NDH-1), PsaE of the photosystem 1 and subunit α of the ferredoxin–thioredoxin reductase have, similar to PetP, a great impact on the photosynthetic electron transport. Finally, a model is presented to illustrate how SH3 domains modulate the photosynthetic electron transport processes in cyanobacteria.