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).
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 |
Autori: | |
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 |
Rivista: | |
Tipologia: | Article (author) |
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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