Fig. 1

Organization of the phazolicin (PHZ) biosynthetic gene cluster. a Comparison of klebsazolicin (KLB) biosynthetic gene cluster (klpACBDE) with the cluster found in the genome of Rhizobium sp. Pop5. Functions of the genes forming the BGCs are listed on the right. The numbers in the middle indicate the extent of identity between the amino acid sequences of the C, B, and D gene products. The sequence of the KLB precursor peptide is shown above its BGC with the leader and core parts indicated. Residues converted to azoles in the final product are highlighted in red. Residues involved in the formation of the N-terminal amidine cycle are highlighted in green. The sequence of the precursor peptide from the newly identified BGC is shown below it. Ser and Cys residues in the sequence of PhzA precursor involved in oxazole and thiazole formation, respectively, are shown in red. Positively charged residues of the predicted core part are highlighted in blue. b Alignment of the amino acid sequences of precursor peptides encoded in phzEACBD BGC and BGCs of PHZ homologs from other Rhizobiales (Rhizobium sp. PDO1-076 and Phyllobacterium myrsinacearum DSM 5893). Ser, Thr, and Cys residues in the predicted core parts of the peptides are shown in red. Positively charged residues are highlighted in blue. c Structure of the fully modified PHZ peptide after the cleavage of the leader. Cyclized residues are shown in red (Thz and Oxz). Positively charged amino acids are highlighted in blue