Cluster of genes encoding KLB biosynthetic pathway was found in genome database using low-level homology of one of the proteins to microcin B17 synthetase.

The activity of KlpE export pump encoded in KLB biosynthetic gene cluster confers self-resistance of the producing bacterium to the action of the antibiotic.

Then an N-terminal leader peptide serves as a recognition element for KlpBCD, a heterocyclase-dehydrogenase complex which converts serine and cysteine residues of KlpA into oxazole and thiazole heterocycles.

Finally, the leader is cleaved off by the action of cellular proteases such as TldD/E, and at the same time KlpBCD activates the new N-terminus to form lactamidine.

Thus, KlpBCD is able to introduce both azole heterocycles and lactamidine linkages, using side chains of Ser/Cys residues and N-terminal amino group as nucleophiles.