We present the functional and structural characterization of the first archaeal thermostable NADP-dependent aldehyde dehydrogenase AlDHPyr1147. In vitro, AlDHPyr1147 catalyzes the irreversible oxidation of short aliphatic aldehydes at 60–85°С, and the affinity of AlDHPyr1147 to the NADP+ at 60°С is comparable to that for mesophilic analogues at 25°С. We determined the structures of the apo form of AlDHPyr1147 (3.04 Å resolution), three binary complexes with the coenzyme (1.90, 2.06, and 2.19 Å), and the ternary complex with the coenzyme and isobutyraldehyde as a substrate (2.66 Å). The nicotinamide moiety of the coenzyme is disordered in two binary complexes, while it is ordered in the ternary complex, as well as in the binary complex obtained after additional soaking with the substrate. AlDHPyr1147 structures demonstrate the strengthening of the dimeric contact (as compared with the analogues) and the concerted conformational flexibility of catalytic Cys287 and Glu253, as well as Leu254 and the nicotinamide moiety of the coenzyme. A comparison of the active sites of AlDHPyr1147 and dehydrogenases characterized earlier suggests that proton relay systems, which were previously proposed for dehydrogenases of this family, are blocked in AlDHPyr1147, and the proton release in the latter can occur through the substrate channel.

中文翻译：

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产自古生菌的NADP依赖的醛脱氢酶sp.1860：结构和功能特征。

我们介绍了第一古细菌热稳定的NADP依赖性醛脱氢酶AlDHPyr1147的功能和结构表征。体外AlDHPyr1147在60–85°С催化短脂肪醛的不可逆氧化，在60°СAlDHPyr1147对NADP +的亲和力与在25°С嗜温类似物的亲和力相当。我们确定了AlDHPyr1147的载脂蛋白形式的结构（分辨率为3.04Å），三个与辅酶形成的二元复合物（1.90、2.06和2.19Å）以及以辅酶和异丁醛为底物的三元复合物（2.66Å）。辅酶的烟酰胺部分在两种二元络合物中是无序的，而在三元络合物中以及在与底物再浸泡后获得的二元络合物中是有序的。AlDHPyr1147结构证明了二聚体接触的增强（与类似物相比）以及催化的Cys287和Glu253一致的构象柔性，以及辅酶的Leu254和烟酰胺部分。AlDHPyr1147和较早表征的脱氢酶活性位点的比较表明，先前提出用于该家族脱氢酶的质子传递系统在AlDHPyr1147中被阻断，质子传递系统中的质子释放可通过底物通道发生。