Structure of the branched-chain keto acid decarboxylase (KdcA) from Lactococcus lactis provides insights into the structural basis for the chemoselective and enantioselective carboligation reaction
Structure of the branched-chain keto acid decarboxylase (KdcA) from Lactococcus lactis provides insights into the structural basis for the chemoselective and enantioselective carboligation reaction
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DOI：
10.1107/s0907444907050433
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发表时间：
2007-12-01
影响因子：
2.2
通讯作者：
Schneider, Gunter
中科院分区：
文献类型：
--
作者：
Berthold, Catrine L.;Gocke, Doerte;Schneider, Gunter
来自乳酸乳球菌的硫胺素二磷酸 (ThDP) 依赖性支链酮酸脱羧酶 (KdcA) 催化 3-甲基-2-氧代丁酸脱羧为 3-甲基丙醛（异丁醛）和 CO2。该酶还能够催化具有极其广泛的底物范围的碳化反应，这一特性使 KdcA 成为 C - C 键形成的潜在有价值的生物催化剂，特别是用于具有高对映选择性的多种取代的 2-羟基酮的酶促合成。重组 Holo-KdcA 和模拟反应中间体的抑制性 ThDP 类似物复合物的晶体结构已确定分辨率分别为 1.6 和 1.8 埃。 KdcA 显示了硫胺素依赖性酶的典型折叠和辅因子-蛋白质相互作用。与大多数其他已知结构的 ThDP 依赖性脱羧酶所展示的四聚体组装相反，KdcA 是同二聚体。晶体结构提供了对酶的底物选择性和立体选择性的结构基础的深入了解，因此适合作为重新设计碳化反应中底物谱的框架。
The thiamin diphosphate (ThDP) dependent branched-chain keto acid decarboxylase (KdcA) from Lactococcus lactis catalyzes the decarboxylation of 3-methyl-2-oxobutanoic acid to 3-methylpropanal (isobutyraldehyde) and CO2. The enzyme is also able to catalyze carboligation reactions with an exceptionally broad substrate range, a feature that makes KdcA a potentially valuable biocatalyst for C - C bond formation, in particular for the enzymatic synthesis of diversely substituted 2-hydroxyketones with high enantioselectivity. The crystal structures of recombinant holo-KdcA and of a complex with an inhibitory ThDP analogue mimicking a reaction intermediate have been determined to resolutions of 1.6 and 1.8 angstrom, respectively. KdcA shows the fold and cofactor - protein interactions typical of thiamin-dependent enzymes. In contrast to the tetrameric assembly displayed by most other ThDP-dependent decarboxylases of known structure, KdcA is a homodimer. The crystal structures provide insights into the structural basis of substrate selectivity and stereoselectivity of the enzyme and thus are suitable as a framework for the redesign of the substrate profile in carboligation reactions.