Two modes of regulation of the fatty acid elongase ELOVL6 by the 3-ketoacyl-CoA reductase KAR in the fatty acid elongation cycle.
Two modes of regulation of the fatty acid elongase ELOVL6 by the 3-ketoacyl-CoA reductase KAR in the fatty acid elongation cycle.
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DOI：
10.1371/journal.pone.0101823
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发表时间：
2014
期刊：
影响因子：
3.7
通讯作者：
Kihara A
中科院分区：
文献类型：
--
作者：
Naganuma T;Kihara A
脂肪酸（FAs）是多种多样的分子，并且这种多样性对于脂质在多种环境条件下发挥其功能是重要的。FA延伸发生在内质网并产生各种FA种类; FA延伸循环由四种不同的酶反应组成。为了有效地驱动这个循环，必须存在FA延伸机器的蛋白质组分的协调调节。然而，人们对这种规定知之甚少。在本研究中，我们进行了生化分析，分别使用FA延伸酶DLPL 6和3-酮脂酰辅酶A还原酶KAR，催化FA延伸周期的第一步和第二步。使用膜组分的体外FA延伸测定表明，在NADPH存在下，HPVL 6活性增强10倍，尽管HPVL 6本身不需要NADPH进行催化。另一方面，KAR在其酶反应中确实使用NADPH作为还原剂。在KAR的存在下，纯化的pEGFPVL 6的活性增强了约3倍。这种效应是KAR酶活性无关的，因为它是在不存在NADPH和KAR突变体中观察到的。然而，KARVL 6酶活性以KAR酶活性依赖性方式进一步增强。因此，KAR通过两种模式调节VL 6。在第一种模式中，KAR可以诱导BMPVL 6的构象变化，使其成为可以进行催化的结构。在第二种模式中，通过KAR将3-酮脂酰-CoA转化为3-羟酰-CoA可促进产物从假定的β VL 6-KAR复合物中释放。
Fatty acids (FAs) are diverse molecules, and such diversity is important for lipids to exert their functions under several environmental conditions. FA elongation occurs at the endoplasmic reticulum and produces a variety of FA species; the FA elongation cycle consists of four distinct enzyme reactions. For this cycle to be driven efficiently, there must exist coordinated regulation of protein components of the FA elongation machinery. However, such regulation is poorly understood. In the present study, we performed biochemical analyses using the FA elongase ELOVL6 and the 3-ketoacyl-CoA reductase KAR, which catalyze the first and second steps of the FA elongation cycle, respectively. In vitro FA elongation assays using membrane fractions demonstrated that ELOVL6 activity was enhanced ∼10-fold in the presence of NADPH, although ELOVL6 itself did not require NADPH for its catalysis. On the other hand, KAR does use NADPH as a reductant in its enzyme reaction. Activity of purified ELOVL6 was enhanced by ∼3-fold in the presence of KAR. This effect was KAR enzyme activity-independent, since it was observed in the absence of NADPH and in the KAR mutant. However, ELOVL6 enzyme activity was further enhanced in a KAR enzyme activity-dependent manner. Therefore, KAR regulates ELOVL6 via two modes. In the first mode, KAR may induce conformational changes in ELOVL6 to become structure that can undergo catalysis. In the second mode, conversion of 3-ketoacyl-CoA to 3-hydroxyacyl-CoA by KAR may facilitate release of the product from the presumed ELOVL6–KAR complex.
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影响因子：
3.5
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