THE HISTIDINE-REVERSIBLE ANTIBIOTIC HERBICOLIN O PRODUCED BY PANTOEA VAGANS C9-1 IS PANTOCIN A

C.A. Ishimaru, T.A. Lansdell, J. Clardy, B. Duffy, T.H.M. Smits

Abstract


Pantoea vagans C9-1 is one of the most effective and reliable biocontrol agents against fire blight, and has been commercialized as Blight Ban C9-1. Production of multiple antibiotics contributes to its antagonism of Erwinia amylovora. Here we describe the genetics, chemical isolation and structure of herbicolin O, the histidine-reversible antibiotic produced by P. vagans C9-1. Mutational analyses indicated that biosynthesis of herbicolin O depends on paaAB and a sequence encoding the peptide precursor of pantocin A. The paaABC gene cluster encoding biosynthesis and autoresistance was located within a 28-kb chromosomal genomic island of the complete genome sequence of P. vagans C9-1. The cluster was cloned and expressed in E. coli and purified antibiotic was isolated using improved methods for small peptides. The 1 H NMR spectra of the C9-1 antibiotic closely resembled those of pantocin A produced by P. agglomerans Eh318. Detailed analysis of the proton spin systems showed that the chemical shift values and coupling constants of the protons in C9-1 herbicolin O correspond exactly to those of pantocin A. Based on these genetic and chemical analyses, herbicolin O and pantocin A are confirmed to be the same antibiotic.

Keywords


fire blight; biocontrol; herbicolin O; peptide antibiotic

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DOI: http://dx.doi.org/10.4454/jpp.v99i0.3910

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EDIZIONI ETS, Pisa, Italy