Crystal structure of 3-hydroxyanthranilate-3,4-dioxygenase I142A from Cupriavidus metallidurans in complex with 4-Cl-3-HAA
Crystal structure of 3-hydroxyanthranilate-3,4-dioxygenase I142A from Cupriavidus metallidurans in complex with 4-Cl-3-HAA
复制标题
来自Cupriavidus Metallidurans 的3-羟基邻氨基苯甲酸-3,4-双加氧酶I142A 与4-Cl-3-HAA 复合物的晶体结构
DOI：
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Aimin Liu
中科院分区：
文献类型：
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作者：
Yu Yang;Fange Liu;Aimin Liu
3-羟基苯甲酸酯3,4-双加氧酶（HAO）是一种铁依赖性蛋白，可激活O2并将两个氧原子插入3-羟基苯甲酸酯（3- haa）中。一个有趣的问题是，即使局部O2浓度和扩散速率相对较低，HAO是如何快速结合O2的。在这里，对HAO结构的仔细检查显示，底物和抑制剂结合的结构表现出封闭的构象，三个疏水环区向催化铁中心移动，而无配体的结构是开放的。我们假设这些环运动增强了O2与HAO和3-HAA二元复合物的结合。我们发现3-HAA的羧基端触发了两个环区的变化，第三个环的运动似乎是由Asn27和Ile142之间的氢键相互作用驱动的。突变分析显示，N27A、I142A和I142P变体不能形成封闭构象，稳态动力学分析表明，这些变体对O2的Km远高于WT HAO。这一观察结果表明，铁中心的疏水性增强是由于初级底物结合后的协同环运动造成的，这是亲水的。考虑到O2是非极性的，二元配合物铁中心疏水性的增加似乎是O2快速结合和激活的必要条件，这解释了3- haa诱导环运动的原因。由于底物结合诱导的开放到封闭的构象变化是常见的，本文报道的结果可能有助于我们进一步了解非血红素铁依赖性双加氧酶中氧是如何富集的。
3-Hydroxyanthranilate 3,4-dioxygenase (HAO) is an iron-dependent protein that activates O2 and inserts both oxygen atoms into 3-hydroxyanthranilate (3-HAA). An intriguing question is how HAO can rapidly bind O2, even though local O2 concentrations and diffusion rates are relatively low. Here, a close inspection of the HAO structures revealed that substrate- and inhibitor-bound structures exhibit a closed conformation with three hydrophobic loop regions moving toward the catalytic iron center, whereas the ligand-free structure is open. We hypothesized that these loop movements enhance O2 binding to the binary complex of HAO and 3-HAA. We found that the carboxyl end of 3-HAA triggers changes in two loop regions and that the third loop movement appears to be driven by an H-bond interaction between Asn27 and Ile142. Mutational analyses revealed that N27A, I142A, and I142P variants cannot form a closed conformation, and steady-state kinetic assays indicated that these variants have a substantially higher Km for O2 than WT HAO. This observation suggested enhanced hydrophobicity at the iron center resulting from the concerted loop movements after the binding of the primary substrate, which is hydrophilic. Given that O2 is nonpolar, the increased hydrophobicity at the iron center of the binary complex appears to be essential for rapid O2 binding and activation, explaining the reason for the 3-HAA–induced loop movements. Because substrate binding-induced open-to-closed conformational changes are common, the results reported here may help further our understanding of how oxygen is enriched in nonheme iron-dependent dioxygenases.
影响因子：
3.4
作者：
Cohen, Jordi;Schulten, Klaus
通讯作者：
Schulten, Klaus
一致。
DOI：
10.1097/iae.0000000000001602
发表时间：
2017
期刊：
Retina (Philadelphia, Pa.)
影响因子：
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作者：
Todorich,Bozho;Thanos,Aristomenis;Yonekawa,Yoshihiro;Thomas,BenjaminJ;Faia,LisaJ;Chang,Emmanuel;Shulman,Julia;Olsen,KarlR;Blair,MichaelP;Shapiro,MichaelP;Ferrone,Philip;Vajzovic,Lejla;Toth,CynthiaA;Lee,ThomasC;Robinson,
通讯作者：
Robinson,
影响因子：
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作者：
Kurnasov, O;Goral, V;Begley, TP
通讯作者：
Begley, TP