Hanson Deborah K, Buhrmaster James C, Wyllie Ryan M, Tira Gregory A, Faries Kaitlyn M, Holten Dewey, Kirmaier Christine, Laible Philip D
Biosciences Division, Argonne National Laboratory, Lemont, IL, USA.
Department of Chemistry, Washington University, St. Louis, MO, USA.
Commun Chem. 2025 Apr 9;8(1):110. doi: 10.1038/s42004-025-01460-y.
Intraprotein electron transfer (ET) requires explicit local control of the environment of cofactors to influence their intermolecular distances, relative orientations, and redox properties. Efficient, longer-range ET often utilizes molecular orbitals of aromatic residues present in the intervening space. Here, revitalization of a vestigial ET pathway in the bacterial photosynthetic reaction center is achieved by scanning with tryptophans to uncover markedly improved routes of electron conduction in a key stabilizing step spanning 15 Å between tetrapyrrole and quinone cofactors. This ET event is maximally enhanced by pairing one or more tryptophans with a threonine to influence quinone binding and/or redox potential. Synergistic effects of these substitutions increase the yield of that ET step to ~95%. Joining these substitutions with mutant residues that improve initial ET steps dramatically enhances transmembrane charge separation via this redesigned version of a pathway that is quantitatively inactive in the native protein-cofactor complex.
蛋白质内电子转移（ET）需要对辅因子的环境进行明确的局部控制，以影响它们的分子间距离、相对取向和氧化还原性质。高效的长程电子转移通常利用存在于中间空间的芳香族残基的分子轨道。在这里，通过用色氨酸进行扫描，在细菌光合反应中心中实现了一条残留电子转移途径的复活，从而在跨越四吡咯和醌辅因子之间15埃的关键稳定步骤中发现了显著改善的电子传导途径。通过将一个或多个色氨酸与苏氨酸配对以影响醌的结合和/或氧化还原电位，这一电子转移事件得到了最大程度的增强。这些取代的协同效应将该电子转移步骤的产率提高到约95%。将这些取代与改善初始电子转移步骤的突变残基相结合，通过这种在天然蛋白质-辅因子复合物中定量无活性的途径的重新设计版本，显著增强了跨膜电荷分离。
