Structure of the enzyme-acyl carrier protein (ACP) substrate gatekeeper complex required for biotin synthesis
Structure of the enzyme-acyl carrier protein (ACP) substrate gatekeeper complex required for biotin synthesis
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DOI：
10.1073/pnas.1207028109
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发表时间：
2012-10-23
影响因子：
11.1
通讯作者：
Cronan, John E.
中科院分区：
文献类型：
--
作者：
Agarwal, Vinayak;Lin, Steven;Cronan, John E.
尽管庚二酰基部分长期以来一直被认为是生物素前体，但这种 C7 α,omega-二羧酸的组装机制直到最近才被阐明。在大肠杆菌中，庚二酸是通过绕过脂肪酸合成途径的严格特异性而产生的。 BioC 甲基化丙二酰硫酯的游离羧基，取代了通常的乙酰基硫酯引物。该非典型引物通过两个脂肪酸合成循环转化为庚二酰酰基载体蛋白（ACP）甲酯。问题是，是什么阻止了该产品进一步伸长？尽管 BioH 很容易在体外裂解该产物，但该酶是非特异性的，这使得其生理底物的分配存在问题，特别是因为另一种酶 BioF 也可以执行这种看门功能。我们报道了BioH与庚二酰-ACP甲酯复合物的2.05埃分辨率共晶结构，并利用该结构证明BioH是看门人，其生理底物是庚二酰-ACP甲酯。
Although the pimeloyl moiety was long known to be a biotin precursor, the mechanism of assembly of this C7 alpha,omega-dicarboxylic acid was only recently elucidated. In Escherichia coli, pimelate is made by bypassing the strict specificity of the fatty acid synthetic pathway. BioC methylates the free carboxyl of a malonyl thioester, which replaces the usual acetyl thioester primer. This atypical primer is transformed to pimeloyl-acyl carrier protein (ACP) methyl ester by two cycles of fatty acid synthesis. The question is, what stops this product from undergoing further elongation? Although BioH readily cleaves this product in vitro, the enzyme is nonspecific, which made assignment of its physiological substrate problematical, especially because another enzyme, BioF, could also perform this gatekeeping function. We report the 2.05-angstrom resolution cocrystal structure of a complex of BioH with pimeloyl-ACP methyl ester and use the structure to demonstrate that BioH is the gatekeeper and its physiological substrate is pimeloyl-ACP methyl ester.