Structure of an acetylating aldehyde dehydrogenase from the thermophilic ethanologen Geobacillus thermoglucosidasius
Structure of an acetylating aldehyde dehydrogenase from the thermophilic ethanologen Geobacillus thermoglucosidasius
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DOI：
10.1002/pro.3027
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发表时间：
2016-11-01
期刊：
影响因子：
8
通讯作者：
Crennell, Susan J.
中科院分区：
文献类型：
--
作者：
Extance, Jonathan;Danson, Michael J.;Crennell, Susan J.
乙酰化醛脱氢酶（AcAldDH）催化辅酶A（CoA）的乙酰化，或者使用NADH作为辅因子从乙酰辅酶A反向产生乙醛。本文报道了热葡糖苷酸地芽孢杆菌AcAldDH（GtAcAldDH）的表达、纯化、酶活性测定和X-射线晶体结构。在结构中，AcAldDH形成紧密结合的二聚体，类似于在其他醇脱氢酶（ADH）结构中所见。在GtAcAldDH中，这些二聚体通过它们的N-末端缔合以形成弱相互作用的四聚体。这种四聚体缔合模式也见于PDB中未发表的AcAldDH，但与所有其他ADH结构（包括在细菌微区室中发现的另一种已发表的AcAldDH）相反，其中二聚体掩埋了包括C-末端在内的大表面积。这种新的缔合模式将活性位点和潜在的反应性酰基酶中间体隔离在四聚体的中心。在其他方面，其结构与其他AcAldDH非常相似，以相应的方式结合辅因子。这种相似性使得能够在G中识别缩短的基底腔。热葡糖苷酶AcAldDH，解释了酶接受的底物长度的限制。
Acetylating aldehyde dehydrogenases (AcAldDH) catalyse the acetylation of CoenzymeA (CoA), or in reverse generate acetaldehyde from Acetyl-CoA using NADH as a co-factor. This article reports the expression, purification, enzyme assay, and X-ray crystal structures of an AcAldDH from Geobacillus thermoglucosidasius (GtAcAldDH) to 2.1 angstrom and in complex with CoA and NAD(+) to 4.0 angstrom. In the structure, the AcAldDH forms a close-knit dimer, similar to that seen in other Alcohol Dehydrogenase (ADH) structures. In GtAcAldDH, these dimers associate via their N-termini to form weakly interacting tetramers. This mode of tetrameric association is also seen in an unpublished AcAldDH deposited in the PDB, but is in contrast to all other ADH structures, (including the one other published AcAldDH found in a bacterial microcompartment), in which the dimers bury a large surface area including the C-termini. This novel mode of association sequesters the active sites and potentially reactive acyl-enzyme intermediates in the center of the tetramer. In other respects, the structure is very similar to the other AcAldDH, binding the cofactors in a corresponding fashion. This similarity enabled the identification of a shortened substrate cavity in G. thermoglucosidasius AcAldDH, explaining the limitations on the length of substrate accepted by the enzyme.