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Bonmatin, JM ; Laprevote, O ; Peypoux, F

Diversity among microbial cyclic lipopeptides : Iturins and surfactins. Activity-structure relationships to design new bioactive agents

Combinatorial Chemistry & High Throughput Screening 6 (6) 541-556

par Administrateur - publié le

Abstract :

A prominent group of bioactive lipopeptides produced by Bacillus species is constituted by iturins, surfactins and lichenysins. Interest in such substances results in their exceptional surfactant power, and their valuable antifungal, antibacterial, antitumoral and anti-Mycoplasma properties. As is typical for peptidic secondary-metabolites synthesized by the polyenzymic pathway, they are produced as mixtures of components varying in the peptidic and/or in the lipidic structure. In the context of structure-activity relationships, it is possible to take advantage of the adaptability of the biosynthesis system by systematically adding selected amino acids in the culture medium of the producing bacterium. When an amino acid is used as the sole nitrogen source, it is inserted directly into selected positions of the peptide sequence, thus amplifying the original structural microheterogeneity via a production of variants. This method revealed very efficient for increasing the amounts of preexisting variants and for building new variants of surfactins and lichenysins but totally inefficient with iturins. In this group, the peptidic diversity strictly depends on the selected strain. So far the screening remained the only method to discover new iturins.