COMMON THEMES IN REDOX CHEMISTRY EMERGE FROM THE X-RAY STRUCTURE OF OILSEED RAPE (BRASSICA-NAPUS) ENOYL ACYL CARRIER PROTEIN REDUCTASE
COMMON THEMES IN REDOX CHEMISTRY EMERGE FROM THE X-RAY STRUCTURE OF OILSEED RAPE (BRASSICA-NAPUS) ENOYL ACYL CARRIER PROTEIN REDUCTASE
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DOI：
10.1016/s0969-2126(01)00227-1
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发表时间：
1995-09-15
期刊：
影响因子：
5.7
通讯作者：
RICE, DW
中科院分区：
文献类型：
--
作者：
RAFFERTY, JB;SIMON, JW;RICE, DW
背景资料：烯酰酰基载体蛋白还原酶（ENR）催化反式-Δ 2-烯酰酰基载体蛋白的NAD（P）H依赖性还原，这是脂肪酸从头生物合成的重要步骤。植物含有NADH依赖性ENR酶和单独的NADPH依赖性ENR酶，其形成可解离的II型脂肪酸合成酶的一部分。高度升高的水平的NADH依赖的酶被发现在成熟的油菜种子（甘蓝型油菜）的脂质沉积过程中。结果：ENR-NAD二元复合物的晶体结构已被确定在1.9埃分辨率和由一个同源四聚体，其中每个亚基形成一个单一的结构域，包括一个七链平行的β折叠侧翼由七个α螺旋。该亚基具有高度类似于二核苷酸结合折叠的拓扑结构。的活性位点已被定位的差傅立叶分析的数据从晶体平衡在NADH.Conclusions：ENR的结构显示出惊人的相似性与差向异构酶和短链醇脱氢酶，特别是3 α，20 β-羟基类固醇脱氢酶（HSD）。与HSD的相似性延伸到稳定过渡态的催化重要赖氨酸的保护和酪氨酸作为碱基的使用-具有由还原化学的不同要求引起的细微修饰。
Background: Enoyl acyl carrier protein reductase (ENR) catalyzes the NAD(P)H-dependent reduction of trans-Delta 2-enoyl acyl carrier protein, an essential step in de novo fatty acid biosynthesis. Plants contain both NADH-dependent and separate NADPH-dependent ENR enzymes which form part of the dissociable type II fatty acid synthetase. Highly elevated levels of the NADH-dependent enzyme are found during lipid deposition in maturing seeds of oilseed rape (Brassica napus).Results: The crystal structure of an ENR-NAD binary complex has been determined at 1.9 Angstrom resolution and consists of a homotetramer in which each subunit forms a single domain comprising a seven-stranded parallel beta sheet flanked by seven alpha helices. The subunit has a topology highly reminiscent of a dinucleotide-binding fold. The active site has been located by difference Fourier analysis of data from crystals equilibrated in NADH.Conclusions: The structure of ENR shows a striking similarity with the epimerases and short-chain alcohol dehydrogenases, in particular, 3 alpha,20 beta-hydroxysteroid dehydrogenase (HSD). The similarity with HSD extends to the conservation of a catalytically important lysine that stabilizes the transition state and to the use of a tyrosine as a base - with subtle modifications arising from differing requirements of the reduction chemistry.