Johansson Per, Hederstedt Lars
Microbiology (Reading). 1999 Mar;145 ( Pt 3):529-538. doi: 10.1099/13500872-145-3-529.
Clusters of genes encoding enzymes for tetrapyrrole biosynthesis were cloned from Bacillus sphaericus, Bacillus stearothermophilus, Brevibacillus brevis and Paenibacillus macerans. The sequences of all hemX genes found, and of a 6.3 kbp hem gene cluster from P. macerans, were determined. The structure of the hem gene clusters was compared to that of other Gram-positive bacteria. The Bacillus and Brevibacillus species have a conserved organization of the genes hemAXCDBL, required for biosynthesis of uroporphyrinogen III (UroIII) from glutamyl-tRNA. In P. macerans, the hem genes for UroIII synthesis are also closely linked but their organization is different: there is no hemX gene and the gene cluster also contains genes, cysG8 and cysG(A)-hemD, encoding the enzymes required for synthesis of sirohaem from UroIII. Bacillus subtilis contains genes for three proteins, NasF, YInD and YInF, with sequence similarity to Escherichia coli CysG, which is a multi-functional protein catalysing sirohaem synthesis from UroIII. It is shown that YInF is required for sirohaem synthesis and probably catalyses the precorrin-2 to sirohaem conversion. YInD probably catalyses precorrin-2 synthesis from UroIII and NasF seems to be specific for nitrite reduction.
从球形芽孢杆菌、嗜热脂肪芽孢杆菌、短短芽孢杆菌和浸麻芽孢杆菌中克隆了编码四吡咯生物合成酶的基因簇。测定了所有已发现的hemX基因的序列，以及来自浸麻芽孢杆菌的一个6.3 kbp hem基因簇的序列。将hem基因簇的结构与其他革兰氏阳性菌的结构进行了比较。芽孢杆菌属和短短芽孢杆菌属具有从谷氨酰-tRNA生物合成尿卟啉原III（UroIII）所需的hemAXCDBL基因的保守组织。在浸麻芽孢杆菌中，用于UroIII合成的hem基因也紧密相连，但它们的组织方式不同：没有hemX基因，并且基因簇还包含从UroIII合成siro血红素所需的酶的编码基因cysG8和cysG(A)-hemD。枯草芽孢杆菌含有三种蛋白质NasF、YInD和YInF的基因，它们与大肠杆菌CysG具有序列相似性（大肠杆菌CysG是一种催化从UroIII合成siro血红素的多功能蛋白质）。结果表明，YInF是siro血红素合成所必需的，可能催化前咕啉-2向siro血红素的转化。YInD可能催化从UroIII合成前咕啉-2，而NasF似乎对亚硝酸盐还原具有特异性。
