Send to

Choose Destination
See comment in PubMed Commons below
J Mol Evol. 2004 Feb;58(2):225-37.

Molecular evolution of hisB genes.

Author information

Dipartimento di Biologia Animale e Genetica, Via Romana 17-19, 1-50125, Firenze, Italy.


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 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).

[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Springer
    Loading ...
    Support Center