Investigations of heme ligation and ligand switching in cytochromes p450 and p420.
Investigations of heme ligation and ligand switching in cytochromes p450 and p420.
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DOI：
10.1021/bi400541v
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发表时间：
2013-08-27
期刊：
影响因子：
2.9
通讯作者：
Champion, Paul M.
中科院分区：
文献类型：
--
作者：
Sun, Yuhan;Zeng, Weiqiao;Benabbas, Abdelkrim;Ye, Xin;Denisov, Ilia;Sligar, Stephen G.;Du, Jing;Dawson, John H.;Champion, Paul M.
人们普遍认为，细胞色素P450 （CYP）的无活性P420形式涉及天然半胱氨酸硫酸酯的质子化，形成中性硫素血红素配体。另一方面，也有人提出，组氨酸的募集取代天然半胱氨酸硫酸盐配体可能是P450→P420转变的基础。在这里，我们讨论了H93G肌红蛋白（Mb）突变体在四氢噻吩（THT）或环五硫醇（CPSH）和压力诱导的细胞色素P420cam （CYP101）存在下的共振拉曼研究，表明组氨酸在CO结合后成为血红素配体。在220 cm−1附近的拉曼模式，通常与血红素蛋白中的铁-组氨酸振动有关，在还原的P420cam和还原的H93G Mb样品中都没有观察到，这表明组氨酸不是还原状态的配体。在诱导型一氧化氮合酶（iNOS）的P420-CO光产物中观察到的221 cm−1拉曼模式是由硫醇结合的亚铁血红素产生的，而在220 cm−1附近模式的缺失也与这一建议的概括不一致。这导致我们将在10 ns P420cam-CO光产物拉曼光谱中观察到的218 cm−1模式分配给铁-组氨酸振动，类似于许多其他组氨酸结合血红素系统。此外，P420cam和H93G类似物的CO加合物的νFe-His和νCO频率的负相关图提供了P420-CO结合状态下组氨酸是血红素配体的支持证据。我们得出结论，当CO结合到亚铁P420状态时，组氨酸配体被招募为血红素配体。在许多CYP系统中，HXC-Fe基序的共同存在使得C→H配体的转换只发生微小的构象变化。一种建议的P420-CO构象包括在近端L螺旋上增加另一个弯，这样，当质子化的Cys配体与血红素分离时，它可以成为螺旋的一部分，血红素被邻近环区的His残基连接。在其他系统中，如iNOS和CYP3A4（其中没有发现HXC-Fe基序），需要稍大的构象变化来招募附近的组氨酸。
It is generally accepted that the inactive P420 form of cytochrome P450 (CYP) involves the protonation of the native cysteine thiolate to form a neutral thiol heme ligand. On the other hand, it has also been suggested that recruitment of a histidine to replace the native cysteine thiolate ligand might underlie the P450→P420 transition. Here we discuss resonance Raman investigations of the H93G myoglobin (Mb) mutant in the presence of tetrahydrothiophene (THT) or cyclopentathiol (CPSH), and on pressure-induced cytochrome P420cam (CYP101), that show a histidine becomes the heme ligand upon CO binding. The Raman mode near 220 cm−1, normally associated with the Fe-histidine vibration in heme proteins, is not observed in either reduced P420cam or the reduced H93G Mb samples, indicating that histidine is not the ligand in the reduced state. The absence of a mode near 220 cm−1 is also inconsistent with a generalization of the suggestion that the 221 cm−1 Raman mode, observed in the P420-CO photoproduct of inducible nitric oxide synthase (iNOS), arises from a thiol-bound ferrous heme. This leads us to assign the 218 cm−1 mode observed in the 10 ns P420cam-CO photoproduct Raman spectrum to a Fe-histidine vibration, in analogy to many other histidine bound heme systems. Additionally, the inverse correlation plots of the νFe-His and νCO frequencies for the CO adducts of P420cam and the H93G analogs provide supporting evidence that histidine is the heme ligand in the P420-CO bound state. We conclude that, when CO binds to the ferrous P420 state, a histidine ligand is recruited as the heme ligand. The common existence of a HXC-Fe motif in many CYP systems allows the C→H ligand switch to occur with only minor conformational changes. One suggested conformation of P420-CO involves the addition of another turn in the proximal L helix so that, when the protonated Cys ligand is dissociated from the heme, it can become part of the helix and the heme is ligated by the His residue from the adjoining loop region. In other systems, such as iNOS and CYP3A4 (where the HXC-Fe motif is not found) a somewhat larger conformational change would be necessary to recuit a nearby histidine.
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DOI：
10.1016/j.bbapap.2010.06.006
发表时间：
2011-01
期刊：
Biochimica et biophysica acta
影响因子：
--
作者：
Lepesheva GI;Waterman MR
通讯作者：
Waterman MR
影响因子：
2.9
作者：
Gruia, Flavin;Ionascu, Dan;Champion, Paul M.
通讯作者：
Champion, Paul M.
影响因子：
2.9
作者：
Franzen, S;Bailey, J;Boxer, SG
通讯作者：
Boxer, SG
DOI：
10.1046/j.1432-1033.2002.03193.x
发表时间：
2002-10-01
期刊：
EUROPEAN JOURNAL OF BIOCHEMISTRY
影响因子：
--
作者：
Franzen, S;Peterson, ES;Boxer, SG
通讯作者：
Boxer, SG
影响因子：
2.9
作者：
Mouro, C;Jung, C;Simonneaux, G
通讯作者：
Simonneaux, G