Molecular evolution of hisB genes
Molecular evolution of hisB genes
复制标题
DOI：
10.1007/s00239-003-2547-x
复制
发表时间：
2004-02-01
影响因子：
3.9
通讯作者：
Fani, R
中科院分区：
文献类型：
--
作者：
Brilli, M;Fani, R
组氨酸生物合成的第6步和第8步分别由咪唑甘油磷酸（IGP）脱水酶（EC 4.2.1.19）和组氨酸二醇磷酸（holp）磷酸酶（EC 3.1.3.15）催化。在肠杆菌、空肠弯曲杆菌和木杆菌/黄单胞菌中，这两种活性与hisB编码的单一双功能多肽有关。另一方面，在古生菌、真核菌和大多数细菌中，这两种活动是由两个不同的基因编码的。在这项工作中，我们报告了对所有可用HisB蛋白的氨基酸序列的比较分析，这使我们能够描述导致当今双功能HisB基因的可能进化途径。根据我们提出的模型，双功能的hisB基因是两个独立的顺子通过结构域改组连接在一起的融合事件的结果。融合事件发生在最近的进化过程中，很可能发生在变形菌谱系中，在γ -和β -分支分离之后。本研究获得的数据证实，祖先DDDD磷酸酶编码基因的同源重复事件起源于大肠杆菌hisB基因的holp -磷酸酶片段和编码DDDD磷酸酶的gmhB基因，后者参与外膜脂多糖（LPS）内核前体的生物合成。
The sixth and eighth steps of histidine biosynthesis are catalyzed by an imidazole glycerolphosphate (IGP)dehydratase (EC 4.2.1.19) and by a histidinol-phosphate (HOL-P) phosphatase (EC 3.1.3.15), respectively. In the enterobacteria, in Campylobacter jejuni and in Xylella/Xanthomonas the two activities are associated with a single bifunctional polypeptide encoded by hisB. On the other hand, in Archaea, Eucarya, and most Bacteria the two activities are encoded by two separate genes. In this work we report a comparative analysis of the amino acid sequence of all the available HisB proteins, which allowed us to depict a likely evolutionary pathway leading to the present-day bifunctional hisB gene. According to the model that we propose, the bifunctional hisB gene is the result of a fusion event between two independent cistrons joined by domain-shuffling. The fusion event occurred recently in evolution, very likely in the proteobacterial lineage after the separation of the gamma- and the beta-subdivisions. Data obtained in this work established that a paralogous duplication event of an ancestral DDDD phosphatase encoding gene originated both the HOL-P phosphatase moiety of the E. coli hisB gene and the gmhB gene coding for a DDDD phosphatase, which is involved in the biosynthesis of a precursor of the inner core of the outer membrane lipopolysaccharides (LPS).