Ligand interactions in the distal heme pocket of Mycobacterium tuberculosis truncated hemoglobin N: roles of TyrB10 and GlnE11 residues.
Ligand interactions in the distal heme pocket of Mycobacterium tuberculosis truncated hemoglobin N: roles of TyrB10 and GlnE11 residues.
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结核分枝杆菌截短血红蛋白 N 的远端血红素口袋中的配体相互作用：TyrB10 和 GlnE11 残基的作用。
DOI：
10.1021/bi060112o
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
Guertin,Michel
中科院分区：
文献类型：
--
作者：
Ouellet,Yannick;Milani,Mario;Couture,Manon;Bolognesi,Martino;Guertin,Michel
The crystallographic structure of oxygenated trHbN fromMycobacterium tuberculosisshowed an extended heme distal site hydrogen-bonding network that includes Y(B10), Q(E11), and the bound O2(Milani, M., et al. (2001)EMBO J.20, 3902−3909). In the present work, we analyze the effects that substitutions at the B10 and E11 positions exert on the heme and its coordinated ligands, using steady-state resonance Raman spectroscopy, absorption spectroscopy and X-ray crystallography. Our results show that (1) residues Y(B10) and Q(E11) control the binding and the ionization state of the heme-bound water molecules in ferric trHbN and are important in keeping the sixth coordination position vacant in deoxy trHbN; (2) residue Q(E11) plays a role in maintaining the integrity of the proximal Fe−His bond in deoxy trHbN; (3) in wild-type oxy-trHbN, the size and hydrogen-bonding capability of residue E11 is important to sustain proper interaction between Y(B10) and the heme-bound O2; (4) CO-trHbN is in a conformational equilibrium, where either the Y(B10) or the Q(E11) residue interacts with the heme-bound CO; and (5) Y(B10) and Q(E11) residues control the conformation (and likely the dynamics) of the protein matrix tunnel gating residue F(E15). These findings suggest that the functional processes of ligand binding and diffusion are controlled in trHbN through the dynamic interaction of residues Y(B10), Q(E11), F(E15), and the heme ligand.
