Synthesising the pigments of life: Structure, function and regulation of metal chelatases in phototrophic bacteria

四吡咯，“生命的色素”，对呼吸、光合作用、氮和硫的循环以及甲烷的生物合成都是必不可少的。四吡啶的独特颜色及其生化特性取决于与金属离子的结合，如绿色叶绿素中的镁或红色血红素中的铁。因此，将金属离子插入四吡咯的酶，称为螯合酶，对地球上大多数能量产生过程至关重要。例如，大量的叶绿素被合成，对光合作用至关重要，光合作用为生物圈提供氧气、食物和能量，血红素对细菌、真菌、植物和哺乳动物的呼吸电子转移至关重要。我们现在需要详细的结构信息来充分了解每一类螯合酶是如何插入特定金属的，以及这些复杂的酶是如何在体内调节的。

Tetrapyrroles, the "pigments of life", are essential for respiration, photosynthesis, the nitrogen and sulphur cycles, and the biosynthesis of methane. The distinctive colours of tetrapyrroles, and their biochemical properties, depend on binding a metal ion such as magnesium in green chlorophylls or iron in hemes, which are red. Therefore, the enzymes that insert the metal ion into tetrapyrroles, called chelatases, are crucially important for most energy-yielding processes on Earth. For example, huge quantities of chlorophylls are synthesised and are essential for photosynthesis, which provides the biosphere with oxygen, food and energy, and heme is essential for respiratory electron transfer in bacteria, fungi, plants and mammals. We now need detailed structural information to gain a full understanding of how each class of chelatase inserts a specific metal, and how these complex enzymes are regulated in vivo.