Journal of Molecular Evolution

, Volume 58, Issue 2, pp 225–237

Molecular Evolution of hisB Genes


DOI: 10.1007/s00239-003-2547-x

Cite this article as:
Brilli, M. & Fani, R. J Mol Evol (2004) 58: 225. doi:10.1007/s00239-003-2547-x


The sixth and eighth steps of histidine biosynthesis are catalyzed by an imidazole glycerol-phosphate (IGP) dehydratase (EC and by a histidinol-phosphate (HOL-P) phosphatase (EC, 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 γ- and the β-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. colihisB 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).


gmhB hisN Evolution of metabolic pathways Gene fusion Gene duplication Patchwork hypothesis 

Copyright information

© Springer-Verlag New York Inc. 2004

Authors and Affiliations

  1. 1.Dipartimento di Biologia Animale e GeneticaVia Romana 17-19, 1-50125, FirenzeItaly

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