Résumé
Albicidins, produced by the sugarcane pathogenic bacterium Xanthomonas albilineans, are potent inhibitors of the bacterial DNA gyrase with Ic50values in nM ranges [1].The structure of albicidins remained unclear for more than three decades after their first description by Birch et al. [2]. After the identification and sequencing of three gene islands, responsible for the albicidin biosynthesis, a PKS-NRPS hybrid, build up by three enzymes, Alb01, Alb05and Alb09 was proposed for the albicidin assembly [3, 4].Most recently we were able to solve the hitherto unknown structure of the main albicidin [5,6] and post NRPS modified derivatives, revealing a unique polyaromatic oligopeptide mainly composed of p-amino benzoic acids. Our in-vitro studies of the non-ribosomal albicidin assembly line and tailoring enzymes provide detailed insights into the biosynthetic machinery of albicidins. Together with our bioinformatic investigations we are able to propose a comprehensive biochemical assembly, expanding the non-ribosomal code of adenylation domains with p-amino benzoic acid derivatives. Furthermore our study revealed a new type of dehydratase domain responsible for the in situ formation and incorporation of cyano-alanine [6]. (Texte intégral)