Schubert H L, Wilson K S, Raux E, Woodcock S C, Warren M J
Department of Chemistry, University of York, Heslington, UK.
Nat Struct Biol. 1998 Jul;5(7):585-92. doi: 10.1038/846.
Biosynthesis of the corrin ring of vitamin B12 requires the action of six S-adenosyl-L-methionine (AdoMet) dependent transmethylases, closely related in sequence. The first X-ray structure of one of these, cobalt-precorrin-4 transmethylase, CbiF, from Bacillus megaterium has been determined to a resolution of 2.4 A. CbiF contains two alphabeta domains forming a trough in which S-adenosyl-L-homocysteine (AdoHcy) binds. The location of AdoHcy and a number of conserved residues, helps define the precorrin binding site. A second crystal form determined at 3.1 A resolution highlights the flexibility of two loops around this site. CbiF employs a unique mode of AdoHcy binding and represents a new class of transmethylase.
维生素B12咕啉环的生物合成需要六种序列密切相关的依赖S-腺苷-L-甲硫氨酸（AdoMet）的转甲基酶的作用。其中一种来自巨大芽孢杆菌的钴-前咕啉-4转甲基酶CbiF的首个X射线结构已确定，分辨率为2.4埃。CbiF包含两个αβ结构域，形成一个槽，S-腺苷-L-高半胱氨酸（AdoHcy）结合在其中。AdoHcy的位置和一些保守残基有助于确定前咕啉结合位点。以3.1埃分辨率确定的第二种晶体形式突出了该位点周围两个环的灵活性。CbiF采用独特的AdoHcy结合模式，代表了一类新型的转甲基酶。
