Influence of the Interdomain Interface on Structural and Redox Properties of Multiheme Proteins.
Influence of the Interdomain Interface on Structural and Redox Properties of Multiheme Proteins.
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域间界面对多血红素蛋白结构和氧化还原性质的影响。
DOI：
10.1021/acs.inorgchem.2c03427
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发表时间：
2022
影响因子：
4.6
通讯作者：
Pletneva,EkaterinaV
中科院分区：
文献类型：
--
作者：
Zhong,Fangfang;Albert,Therese;Moënne-Loccoz,Pierre;Pletneva,EkaterinaV
多血红素蛋白在氮和硫的能量转换和生物地球化学循环中起着重要作用。以双铁血红素细胞色素4(C4)为模型，阐明了结构域间界面对其HEME A和B中铁中心性质的影响。分离的单血红素结构域SC4-A和C4-B，以及全长的DIHEMEC4及其Met-to-His配体变体，通过各种光谱和稳定性测量进行了表征。在这两个分离的结构域中，血红素铁在pH为5.0时与全长C4一样被Met/His-连接，但在较高pH时变为His/His-连接的inc4-B。结构域内接触inc4-A受C4-A和C4-B结构域分离的影响最小，孤立的C4-A被折叠。相反，分离的C4-B部分展开，与C4-A的界面引导该结构域的折叠。即使没有多肽连接物，4-A和C4-B结构域也有相互作用的倾向。热力学循环揭示了单体折叠的孤立结构域的性质，表明界面稳定的是亚铁(FeII)，而不是铁(FeIII)C4-A和C4-B。本研究阐明了界面对多血红素蛋白质结构和氧化还原性质的影响，丰富了我们对氧化还原依赖的络合作用的理解。
Multiheme proteins are important in energy conversion and biogeochemical cycles of nitrogen and sulfur. A diheme cytochromec4(c4) was used as a model to elucidate roles of the interdomain interface on properties of iron centers in its hemes A and B. Isolated monoheme domainsc4-A andc4-B, together with the full-length dihemec4and its Met-to-His ligand variants, were characterized by a variety of spectroscopic and stability measurements. In both isolated domains, the heme iron is Met/His-ligated at pH 5.0, as in the full-lengthc4, but becomes His/His-ligated inc4-B at higher pH. Intradomain contacts inc4-A are minimally affected by the separation ofc4-A andc4-B domains, and isolatedc4-A is folded. In contrast, the isolatedc4-B is partially unfolded, and the interface withc4-A guides folding of this domain. Thec4-A andc4-B domains have the propensity to interact even without the polypeptide linker. Thermodynamic cycles have revealed properties of monomeric folded isolated domains, suggesting that ferrous (FeII), but not ferric (FeIII)c4-A andc4-B, is stabilized by the interface. This study illustrates the effects of the interface on tuning structural and redox properties of multiheme proteins and enriches our understanding of redox-dependent complexation.