Deciphering the d1 haem biosynthesis pathway and its relationship to a novel anaerobic route to protohaem

许多蛋白质含有血红素(如血液中的血红蛋白)，它是一个中间带有铁原子的环状分子。在一些蛋白质中，血红素被修饰，就像在全球氮循环中催化关键反应的酶一样。这个反应是将亚硝酸盐还原为一氧化氮，修饰后的血红素称为d1。我们知道很多关于“标准”血红素(原血红素)是如何在细胞中用简单得多的化学物质制成的，但我们几乎不知道重要的D1血红素是如何制成的。我们的主要目标是发现细胞构建D1Hem物种的步骤。出人意料的是，最近出现的某些被归类为古生菌的生物没有可识别的血红素合成途径，还原硫酸盐的细菌也是如此。这两类生物不包含亚硝酸还原酶，但确实包含一些预测的蛋白质，这些蛋白质与D1Hem合成中涉及的蛋白质非常相似。因此，我们希望也有助于理解一条与有趣的进化相关的新的血红素合成路线。

Many proteins contain haem (eg hemoglobin of the blood) which is a ring molecule with an iron atom in the middle. In some proteins the haem is modified, as is the case in an enzyme that catalyses a key reaction in the global nitrogen cycle. This reaction is reduction of nitrite to nitric oxide and the modified haem is called d1. We know a great deal about how 'standard' haem (protohaem) is made in cells from much simpler chemicals but we know almost nothing about how the vital d1 haem is made. It is our major aim to discover the steps whereby cells construct the d1 haem species. Unexpectedly, it has recently emerged that certain kinds of organisms classified as archaea do not have a recognisable haem synthesis pathway and the same is true for bacteria that reduce sulfate. The two classes of organisms do not contain nitrite reductase but do contain some predicted proteins which are very similar to those implicated in d1 haem synthesis. Thus we expect also to contribute to understanding a novel haem synthesis route with which interesting evolutionary implications are associated.