Influence of substrate modification and C-terminal truncation on the active site structure of substrate-bound heme oxygenase from Neisseriae meningitidis. A 1H NMR study.
Influence of substrate modification and C-terminal truncation on the active site structure of substrate-bound heme oxygenase from Neisseriae meningitidis. A 1H NMR study.
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DOI：
10.1021/bi200978g
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发表时间：
2011-10-18
期刊：
影响因子：
2.9
通讯作者：
La Mar, Gerd N.
中科院分区：
文献类型：
--
作者：
Peng, Dungeng;Satterlee, James D.;Ma, Li-Hua;Dallas, Jerry L.;Smith, Kevin M.;Zhang, Xuhong;Sato, Michihiko;La Mar, Gerd N.
血红素加氧酶（HO）是从病原菌N.在脑膜炎病毒中，NmHO与哺乳动物HO具有许多相同的性质，但也表现出一些关键的差异。晶体结构看起来更紧凑，并且晶体未检测到的C-末端与溶液中的底物相互作用。底物蛋白质的独特性质，特别是吡咯-I/II-螺旋-2，NmHO中的外周相互作用通过2D 1H NMR探测，以揭示控制底物取向的独特结构特征。底物取向异构的热力学映射为个别乙烯基→甲基→氢取代和酶C-末端缺失的底物。NmHO表现出显着更强的取向偏好，反映了更强的和选择性的吡咯-I/II与蛋白质基质的相互作用，比在哺乳动物HO。因此，用氢取代庞大的乙烯基导致底物在活性位点中围绕α，γ-内消旋轴旋转180°。一个“崩溃”的基板口袋作为基板尺寸减小反映在运动的螺旋-2向基板所示的显着和选择性增加的NOESY交叉峰强度，增加空间Fe-CN倾斜反映在主磁轴的取向，和减少空间限制控制芳环重定向的速率。NmHO的活性位点对于天然血红素似乎是“应激的”，并且在用氢取代乙烯基后其“崩溃”导致底物亲和力增加约102倍。C-末端与活性位点的相互作用使结晶学原血红素取向不稳定约0.7 kcal/mol，这与优化His 207-Asp 27 H-键一致。活性位点的影响“应力”的产品发布进行了讨论。
Heme oxygenase, HO, from the pathogenic bacterium N. meningitidis, NmHO, which secures host iron, shares many properties with mammalian HOs, but also exhibits some key differences. The crystal structure appears more compact and the crystal-undetected C-terminus interacts with substrate in solution. The unique nature of substrate-protein, specifically pyrrole-I/II-helix-2, peripheral interactions in NmHO are probed by 2D 1H NMR to reveal unique structural features controlling substrate orientation. The thermodynamics of substrate orientational isomerism are mapped for substrates with individual vinyl → methyl → hydrogen substitutions and with enzyme C-terminal deletions. NmHO exhibits significantly stronger orientational preference, reflecting much stronger and selective pyrrole-I/II interactions with the protein matrix, than in mammalian HOs. Thus, replacing bulky vinyls with hydrogens results in a 180° rotation of substrate about the α,γ-meso axis in the active site. A "collapse" of the substrate pocket as substrate size decreases is reflected in movement of helix-2 toward the substrate as indicated by significant and selective increased NOESY cross peak intensity, increase in steric Fe-CN tilt reflected in the orientation of the major magnetic axis, and decrease in steric constraints controlling the rate of aromatic ring reorientation. The active site of NmHO appears "stressed" for native protohemin and its "collapse" upon replacing vinyls by hydrogen leads to a factor ~102 increase in substrate affinity. Interaction of the C-terminus with the active site destabilizes the crystallographic protohemin orientation by ~0.7 kcal/mol, which is consistent with optimizing the His207-Asp27 H-bond. Implications of the active site "stress" for product release are discussed.
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影响因子：
2.9
作者：
Ogura, Hiroshi;Evans, John P.;Peng, Dungeng;Satterlee, James D.;de Montellano, Paul R. Ortiz;La Mar, Gerd N.
通讯作者：
La Mar, Gerd N.
影响因子：
3.9
作者：
Ma, Li-Hua;Liu, Yangzhong;Zhang, Xuhong;Yoshida, Tadashi;Mar, Gerd N. La
通讯作者：
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影响因子：
2.9
作者：
HERNANDEZ, G;WILKS, A;LAMAR, GN
通讯作者：
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影响因子：
15
作者：
Caignan, GA;Deshmukh, R;Rivera, M
通讯作者：
Rivera, M
影响因子：
15
作者：
Ma, Li-Hua;Liu, Yangzhong;La Mar, Gerd N.
通讯作者：
La Mar, Gerd N.