The bacteriohemerythrin from Methylococcus capsulatus (Bath): Crystal structures reveal that Leu114 regulates a water tunnel
The bacteriohemerythrin from Methylococcus capsulatus (Bath): Crystal structures reveal that Leu114 regulates a water tunnel
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DOI：
10.1016/j.jinorgbio.2015.04.001
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发表时间：
2015-09-01
影响因子：
3.9
通讯作者：
Chan, Sunney I.
中科院分区：
文献类型：
--
作者：
Chen, Kelvin H. -C.;Chuankhayan, Phirnonphan;Chan, Sunney I.
来自荚膜甲基球菌（Methylococcus capsulatus, Bath）的细菌甲氧氰酯（bacteriohemerythrin, McHr）是一种氧载体，作为一种转运体，将O-2从细菌细胞体的细胞质溶胶中运送到位于胞质内膜的颗粒甲烷单加氧酶中进行甲烷氧化。本文报道了重组野生型（WT） McHr及其L114A、L114Y和L114F突变体的x射线蛋白晶体结构。WT的结构揭示了McHr中可能存在的水隧道，这可能与海洋无脊椎动物中相对于氰菊酯更快的自氧化有关。由于Leu114位于这条假定的水通道的末端，该残基的疏水侧链似乎在控制自氧化所需水分子的进入方面发挥了突出作用。通过将WT McHr的自氧化速率与L114A、L114Y和L114F突变体的自氧化速率进行比较，验证了这一假设。生化数据与x射线结构提供的各种McHr蛋白中假定的水隧道分析得出的结构见解相关。(C) 2015爱思唯尔公司版权所有。
The bacteriohemerythrin (McHr) from Methylococcus capsulatus (Bath) is an oxygen carrier that serves as a transporter to deliver O-2 from the cytosol of the bacterial cell body to the particulate methane monooxygenase residing in the intracytoplasmic membranes for methane oxidation. Here we report X-ray protein crystal structures of the recombinant wild type (WT) McHr and its L114A, L114Y and L114F mutants. The structure of the WT reveals a possible water tunnel in the McHr that might be linked to its faster autoxidation relative to hemerythrin in marine invertebrates. With Leu114 positioned at the end of this putative water tunnel, the hydrophobic side chain of this residue seems to play a prominent role in controlling the access of the water molecule required for autoxidation. This hypothesis is examined by comparing the autoxidation rates of the WT McHr with those of the L114A, L114Y and L114F mutants. The biochemical data are correlated with structural insights derived from the analysis of the putative water tunnels in the various McHr proteins provided by the X-ray structures. (C) 2015 Elsevier Inc. All rights reserved.