德国布伦瑞克工业大学Tobias Kruse团队报道了钼酸盐插入蝶呤基钼辅因子的机理。相关研究成果发表在2021年6月28日出版的《Nature Chemistry》。

钼辅因子（Moco）存在于许多对生物过程至关重要的重要酶的活性部位。在Moco中螯合钼的双齿配体是吡喃蝶呤二硫烯（molybdepterin，MPT）。然而，钼酸盐插入MPT的机制和Moco插入吡喃蝶呤钼酶之前的结构尚不清楚。

该文中，研究人员报告了最后的成熟步骤，其中腺苷酸化MPT（MPT-AMP）和钼酸盐是底物。拟南芥Mo插入酶变异体Cnx1E S269D D274S的X射线晶体学鉴定腺苷酸化Moco（Moco-AMP）是该反应序列中一个意外的中间产物。X射线吸收光谱揭示了Moco在Cnx1E活性中心的第一配位球结构。

研究人员利用这些结构信息推断了钼酸盐插入MPT–AMP的机制。鉴于其高度的结构和序列相似性，研究人员认为这一机制适用于所有真核生物Mo插入酶。

附：英文原文

Title: Mechanism of molybdate insertion into pterin-based molybdenum cofactors

Author: Corinna Probst, Jing Yang, Joern Krausze, Thomas W. Hercher, Casseday P. Richers, Thomas Spatzal, Khadanand KC, Logan J. Giles, Douglas C. Rees, Ralf R. Mendel, Martin L. Kirk, Tobias Kruse

Issue&Volume: 2021-06-28

Abstract: The molybdenum cofactor (Moco) is found in the active site of numerous important enzymes that are critical to biological processes. The bidentate ligand that chelates molybdenum in Moco is the pyranopterin dithiolene (molybdopterin, MPT). However, neither the mechanism of molybdate insertion into MPT nor the structure of Moco prior to its insertion into pyranopterin molybdenum enzymes is known. Here, we report this final maturation step, where adenylated MPT (MPT–AMP) and molybdate are the substrates. X-ray crystallography of the Arabidopsis thaliana Mo-insertase variant Cnx1E S269D D274S identified adenylated Moco (Moco–AMP) as an unexpected intermediate in this reaction sequence. X-ray absorption spectroscopy revealed the first coordination sphere geometry of Moco trapped in the Cnx1E active site. We have used this structural information to deduce a mechanism for molybdate insertion into MPT–AMP. Given their high degree of structural and sequence similarity, we suggest that this mechanism is employed by all eukaryotic Mo-insertases.

DOI: 10.1038/s41557-021-00714-1

Source: https://www.nature.com/articles/s41557-021-00714-1