Electronic control of ligand-binding preference of a myoglobin mutant
Electronic control of ligand-binding preference of a myoglobin mutant
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肌红蛋白突变体配体结合偏好的电子控制
DOI：
10.1021/ic5011924
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发表时间：
2014
影响因子：
4.6
通讯作者：
Y. Yamamoto
中科院分区：
文献类型：
--
作者：
R. Nishimura;D. Matsumoto;T. Shibata;S. Yanagisawa;T. Ogura;H. Tai;T. Matsuo;S. Hirota;S. Neya;A. Suzuki;Y. Yamamoto
抹香鲸肌红蛋白 (Mb) 的 L29F 突变体，其中亮氨酸 29 残基被苯丙氨酸 (Phe) 取代，显示出对氧 (O2) 具有非常高的亲和力，这可能是由于突变蛋白中血红素 Fe 原子结合的 O2 通过与引入的 Phe29 的独特静电相互作用得到稳定，此外还与 His64 形成众所周知的氢键 [Carver, T. E.；布兰特利，R.E.；辛格尔顿，E.W.；阿杜伊尼，R.M.；奎林，M.L.；菲利普斯，G.N.，Jr.；奥尔森，J.S.J.生物。化学,1992, 267, 14443–14450]。我们分析了用具有不同电子密度的血红素铁原子的化学修饰血红素辅助因子重构的 L29F 突变蛋白的 O2 和一氧化碳 (CO) 结合特性，以确定血红素铁原子 (ρFe) 的电子密度变化对 O2 与 CO 辨别的影响。研究表明，蛋白质对O2相对于CO的优先结合是通过增加ρFe来实现的，而普通配体结合偏好，即CO相对于O2对蛋白质的优先结合是通过降低ρFe来实现的。因此，L29F 突变蛋白的 O2 和 CO 结合偏好可以通过改变 ρFe 对内在血红素 Fe 反应性进行电子调节来控制。本研究强调了通过血红素电子结构调节内在血红素 Fe 反应性在 Mb 功能调节中的重要性。
The L29F mutant of sperm whale myoglobin (Mb), where the leucine 29 residue was replaced by phenylalanine (Phe), was shown to exhibit remarkably high affinity to oxygen (O2), possibly due to stabilization of the heme Fe atom-bound O2in the mutant protein through a proposed unique electrostatic interaction with the introduced Phe29, in addition to well-known hydrogen bonding with His64 [Carver, T. E.; Brantley, R. E.; Singleton, E. W.; Arduini, R. M.; Quillin, M. L.; Phillips, G. N., Jr.; Olson, J. S.J. Biol. Chem.,1992, 267, 14443–14450]. We analyzed the O2and carbon monoxide (CO) binding properties of the L29F mutant protein reconstituted with chemically modified heme cofactors possessing a heme Fe atom with various electron densities, to determine the effect of a change in the electron density of the heme Fe atom (ρFe) on the O2versus CO discrimination. The study demonstrated that the preferential binding of O2over CO by the protein was achieved through increasing ρFe, and the ordinary ligand-binding preference, that is, the preferential binding of CO over O2, by the protein was achieved through decreasing ρFe. Thus, the O2and CO binding preferences of the L29F mutant protein could be controlled through electronic modulation of intrinsic heme Fe reactivity through a change in ρFe. The present study highlighted the significance of the tuning of the intrinsic heme Fe reactivity through the heme electronic structure in functional regulation of Mb.