Conformational Plasticity in Human Heme-Based Dioxygenases.
Conformational Plasticity in Human Heme-Based Dioxygenases.
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DOI：
10.1021/jacs.0c09970
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发表时间：
2021-02-03
影响因子：
15
通讯作者：
Yeh SR
中科院分区：
文献类型：
--
作者：
Pham KN;Lewis-Ballester A;Yeh SR
人吲哚胺2,3-双加氧酶1 （hIDO1）和人色氨酸双加氧酶（hTDO）是沿犬尿氨酸途径降解必需氨基酸l -色氨酸（Trp）的两个重要血红素蛋白。这两种酶具有相似的活性位点结构和类似的催化机制，但它们表现出各种不同的功能特性。在这里，我们使用一氧化碳（CO）作为结构探针来探究这两种酶的功能是如何在它们的结构中编码的。通过x射线晶体学，我们发现了一种意想不到的光化学中间体被捕获在hIDO1-CO-Trp复合物的晶体中，在低温（100 K）下，x射线将CO从血红素铁中光解出来。CO光解引起底物色氨酸和被光解的CO从活性位点大规模迁移到临时结合位点Sa*。尽管在冷冻条件下蛋白质的运动受到严重限制，但它仍伴随着活性位点环JK-LoopC的大构象变化，这凸显了hIDO1蛋白显着的构象可塑性。对hTDO-CO-Trp复合物晶体的比较研究表明，在类似的x射线照射下，CO和Trp仍然结合在活性位点，表明蛋白质结构更加刚性。这些数据为血红素双加氧酶的结构和功能关系提供了重要的新见解，并为基于结构设计靶向它们的抑制剂提供了新的指导。
Human indoleamine 2,3-dioxygenase 1 (hIDO1) and human tryptophan dioxygenase (hTDO) are two important heme proteins that degrade the essential amino acid, L-tryptophan (Trp), along the kynurenine pathway. The two enzymes share a similar active site structure and an analogous catalytic mechanism, but they exhibit a variety of distinct functional properties. Here we used carbon monoxide (CO) as a structural probe to interrogate how the functionalities of the two enzymes are encoded in their structures. With X-ray crystallography, we detected an unexpected photochemical intermediate trapped in a crystal of the hIDO1-CO-Trp complex, where CO is photolyzed from the heme iron by X-rays at cryogenic temperatures (100 K). The CO photolysis triggers a large-scale migration of the substrate Trp, as well as the photolyzed CO, from the active site to a temporary binding site, Sa*. It is accompanied by a large conformational change to an active site loop, JK-LoopC, despite the severely restricted protein motion under the frozen conditions, which highlights the remarkable conformational plasticity of the hIDO1 protein. Comparative studies of a crystal of the hTDO-CO-Trp complex show that CO and Trp remain bound in the active site under comparable X-ray illumination, indicating a much more rigid protein architecture. The data offer important new insights into the structure and function relationships of the heme-based dioxygenases and provide new guidelines for structure-based design of inhibitors targeting them.
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影响因子：
3.6
作者：
Kanai M;Funakoshi H;Takahashi H;Hayakawa T;Mizuno S;Matsumoto K;Nakamura T
通讯作者：
Nakamura T
影响因子：
2.9
作者：
Álvarez L;Lewis-Ballester A;Roitberg A;Estrin DA;Yeh SR;Marti MA;Capece L
通讯作者：
Capece L
DOI：
10.1107/s0907444904019158
发表时间：
2004-12-01
影响因子：
2.2
作者：
Emsley, P;Cowtan, K
通讯作者：
Cowtan, K
影响因子：
15
作者：
Efimov, Igor;Basran, Jaswir;Raven, Emma Lloyd
通讯作者：
Raven, Emma Lloyd
影响因子：
7.3
作者：
Crosignani, Stefano;Bingham, Patrick;Wythes, Martin
通讯作者：
Wythes, Martin