Evidence for functional and regulatory cross-talk between the tricarboxylic acid cycle 2-oxoglutarate dehydrogenase complex and 2-oxoadipate dehydrogenase on the l-lysine, l-hydroxylysine and l-tryptophan degradation pathways from studies in vitro.
Evidence for functional and regulatory cross-talk between the tricarboxylic acid cycle 2-oxoglutarate dehydrogenase complex and 2-oxoadipate dehydrogenase on the l-lysine, l-hydroxylysine and l-tryptophan degradation pathways from studies in vitro.
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DOI：
10.1016/j.bbabio.2018.05.001
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发表时间：
2018-09
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影响因子：
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通讯作者：
N. Nemeria;G. Gerfen;Luying Yang;Xu Zhang;F. Jordan
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文献类型：
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作者：
N. Nemeria;G. Gerfen;Luying Yang;Xu Zhang;F. Jordan
本文报道了体外实验结果，表明人2-氧代戊二酸脱氢酶复合物（hOGDHc）（三羧酸循环（TCA循环）中的关键调节酶）与来自l-赖氨酸、l-羟基赖氨酸和l-色氨酸的最终降解途径的新型2-氧代己二酸脱氢酶复合物（hOADHc）之间存在功能和调节串扰。利用hOGDHc和hOADHc在体外组装的研究结果表明：（1）尽管两种复合物具有相同的二氢硫辛酰琥珀酰转移酶（hE 20）和二氢硫辛酰脱氢酶（hE 3）组分，但它们对底物的选择性（kcat/Km）不同;（ii）根据使用位点特异性标记的hE 2 o衍生蛋白的荧光滴定，二元hE 1 o-hE 2 o和hE 1a-hE 2 o亚复合物的不同结合模式得到了证据;（iii）类似于hE 1 o，hE 1a也从2-氧代己二酸酯形成ThDP-烯胺自由基（电子顺磁共振检测）在氧化半反应;（iv）两种复合物在还原半反应中从O2产生超氧化物/H2 O2，表明hE 1 o，hE1a（在它们的复合物内）可以分别是2-酮戊二酸和2-酮己二酸在线粒体中产生活性氧的来源;（v）基于我们的发现，我们推测hE 20除了作为转琥珀酰酶之外，还可以作为转戊二酸酶，这是其他人提出的作用;（vi）由hOADH c产生的戊二酰辅酶A抑制hE 1 o，琥珀酰辅酶A也是如此，表明两种复合物在不同代谢途径上的调节串扰。
Herein are reported findingsin vitrosuggesting both functional and regulatory cross-talk between the human 2-oxoglutarate dehydrogenase complex (hOGDHc), a key regulatory enzyme within the tricarboxylic acid cycle (TCA cycle), and a novel 2-oxoadipate dehydrogenase complex (hOADHc) from the final degradation pathway ofl-lysine,l-hydroxylysine andl-tryptophan. The following could be concluded from our studies by using hOGDHc and hOADHc assembled from their individually expressed componentsin vitro: (i) Different substrate preferences (kcat/Km) were displayed by the two complexes even though they share the same dihydrolipoyl succinyltransferase (hE2o) and dihydrolipoyl dehydrogenase (hE3) components; (ii) Different binding modes were in evidence for the binary hE1o-hE2o and hE1a-hE2o subcomplexes according to fluorescence titrations using site-specifically labeled hE2o-derived proteins; (iii) Similarly to hE1o, the hE1a also forms the ThDP-enamine radical from 2-oxoadipate (electron paramagnetic resonance detection) in the oxidative half reaction; (iv) Both complexes produced superoxide/H2O2from O2in the reductive half reaction suggesting that hE1o, and hE1a (within their complexes) could both be sources of reactive oxygen species generation in mitochondria from 2-oxoglutarate and 2-oxoadipate, respectively; (v) Based on our findings, we speculate that hE2o can serve as a trans-glutarylase, in addition to being a trans-succinylase, a role suggested by others; (vi) The glutaryl-CoA produced by hOADHc inhibits hE1o, as does succinyl-CoA, suggesting a regulatory cross-talk between the two complexes on the different metabolic pathways.