Cobaltochelatase in aerobic cobalamin biosynthesis is a complex composed of three subunits. The large subunit CobN is a 140‐kDa protein and is homologous to the ChlH subunit of magnesium chelatase. Previously we have reported the 2.5‐Å structure of a cyanobacterial ChlH. Here we present the 1.8‐Å structure of CobN from Mycobacterium tuberculosis. The overall structure of CobN and ChlH is similar, but significant difference occurs in the head domain. Structural comparison of domains between the two proteins unravels candidate regions for substrate binding and helps to locate a triad of residues that may be essential for metal ion binding.

中文翻译：

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结核分枝杆菌钴螯合酶大亚基的晶体结构

需氧钴胺素生物合成中的钴螯合酶是由三个亚基组成的复合物。大亚基 CobN 是一种 140 kDa 的蛋白质，与镁螯合酶的 ChlH 亚基同源。之前我们已经报道了蓝细菌 ChlH 的 2.5-Å 结构。在这里，我们展示了来自结核分枝杆菌的 CobN 的 1.8-Å 结构。CobN 和 ChlH 的整体结构相似，但在头部域出现显着差异。两种蛋白质之间结构域的结构比较揭示了底物结合的候选区域，并有助于定位可能对金属离子结合至关重要的三联体残基。