Role of the distal hydrogen-bonding network in regulating oxygen affinity in the truncated hemoglobin III from Campylobacter jejuni.
Role of the distal hydrogen-bonding network in regulating oxygen affinity in the truncated hemoglobin III from Campylobacter jejuni.
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DOI：
10.1021/bi101137n
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发表时间：
2011-05-17
期刊：
影响因子：
2.9
通讯作者：
Estrin DA
中科院分区：
文献类型：
--
作者：
Arroyo Mañez P;Lu C;Boechi L;Martí MA;Shepherd M;Wilson JL;Poole RK;Luque FJ;Yeh SR;Estrin DA
含血红素蛋白的氧亲和力由许多因素决定，例如通过氢键相互作用稳定血红素结合氧的远端残基的性质和构象。来自空肠弯曲杆菌（Ctb）的截断血红蛋白III在远端含有三个潜在的氢键供体：TyrB10、TrpG8和HisE7。先前的研究表明，由于涉及三个远端残基的交错氢键网络，Ctb表现出极慢的氧解离速率。在这里，我们研究了Ctb突变体G8WF的结构和动力学特性，并采用最先进的计算机模拟方法研究了G8WF突变体与野生型蛋白和先前研究的E7HL和/或B10YF突变体的O2加合物的特性。我们的数据表明，Ctb独特的氧结合特性是由血红素结合配体与周围TyrB10、TrpG8和HisE7残基之间的氢键相互作用决定的。
Oxygen affinity in heme-containing proteins is determined by a number of factors, such as the nature and conformation of the distal residues that stabilize the heme bound-oxygen via hydrogen-bonding interactions. The truncated hemoglobin III from Campylobacter jejuni (Ctb) contains three potential hydrogen-bond donors in the distal site: TyrB10, TrpG8, and HisE7. Previous studies suggested that Ctb exhibits an extremely slow oxygen dissociation rate due to an interlaced hydrogen-bonding network involving the three distal residues. Here we have studied the structural and kinetic properties of the G8WF mutant of Ctb and employed state-of-the-art computer simulation methods to investigate the properties of the O2 adduct of the G8WF mutant, with respect to those of the wild-type protein and the previously studied E7HL and/or B10YF mutants. Our data indicate that the unique oxygen binding properties of Ctb are determined by the interplay of hydrogen-bonding interactions between the heme-bound ligand and the surrounding TyrB10, TrpG8, and HisE7 residues.