The sixth and eighth steps of histidine biosynthesis are catalyzed by an imidazole glycerolphosphate (IGP)dehydratase (EC 220.127.116.11) and by a histidinol-phosphate (HOL-P) phosphatase (EC 18.104.22.168), 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).
Molecular evolution of hisB genes / M. Brilli, R. Fani. - In: JOURNAL OF MOLECULAR EVOLUTION. - ISSN 0022-2844. - 58:2(2004), pp. 225-237.
|Titolo:||Molecular evolution of hisB genes|
|Parole Chiave:||gmhB; hisN; evolution of metabolic pathways; gene fusion; gene duplication; patchwork hypothesis|
|Settore Scientifico Disciplinare:||Settore BIO/19 - Microbiologia Generale|
|Data di pubblicazione:||2004|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1007/s002239-003-2547-x|
|Appare nelle tipologie:||01 - Articolo su periodico|
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