来自嗜甲基甲基杆菌AM1的亚甲基-四氢甲蝶呤脱氢酶的结构

Structure of methylene-tetrahydromethanopterin dehydrogenase from methylobacterium extorquens AM1.

作者信息

Ermler Ulrich, Hagemeier Christoph H, Roth Annette, Demmer Ulrike, Grabarse Wolfgang, Warkentin Eberhard, Vorholt Julia A

机构信息

Max-Planck-Institut für Biophysik, Heinrich-Hoffmann-Strasse 7, D-60528 Frankfurt am Main, Germany.

出版信息

Structure. 2002 Aug;10(8):1127-37. doi: 10.1016/s0969-2126(02)00802-x.

DOI:10.1016/s0969-2126(02)00802-x

PMID:12176390

Abstract

NADP-dependent methylene-H(4)MPT dehydrogenase, MtdA, from Methylobacterium extorquens AM1 catalyzes the dehydrogenation of methylene-tetrahydromethanopterin and methylene-tetrahydrofolate with NADP(+) as cosubstrate. The X-ray structure of MtdA with and without NADP bound was established at 1.9 A resolution. The enzyme is present as a homotrimer. The alpha,beta fold of the monomer is related to that of methylene-H(4)F dehydrogenases, suggesting a common evolutionary origin. The position of the active site is located within a large crevice built up by the two domains of one subunit and one domain of a second subunit. Methylene-H(4)MPT could be modeled into the cleft, and crucial active site residues such as Phe18, Lys256, His260, and Thr102 were identified. The molecular basis of the different substrate specificities and different catalytic demands of MtdA compared to methylene-H(4)F dehydrogenases are discussed.

摘要

来自嗜甲基甲基杆菌AM1的NADP依赖性亚甲基-H(4)MPT脱氢酶MtdA，以NADP(+)作为共底物，催化亚甲基-四氢甲蝶呤和亚甲基-四氢叶酸的脱氢反应。在1.9埃分辨率下确定了结合和未结合NADP的MtdA的X射线结构。该酶以同三聚体形式存在。单体的α、β折叠与亚甲基-H(4)F脱氢酶的相关，表明有共同的进化起源。活性位点位于由一个亚基的两个结构域和第二个亚基的一个结构域构成的大裂缝内。亚甲基-H(4)MPT可以模拟到裂缝中，并鉴定出关键的活性位点残基，如苯丙氨酸18、赖氨酸256、组氨酸260和苏氨酸102。讨论了与亚甲基-H(4)F脱氢酶相比，MtdA不同底物特异性和不同催化需求的分子基础。