Dual substrate-controlled kinase activity leads to polyphosphorylated lasso peptides

Lasso peptides are characterized by their peculiar lariat knot-like structure. Except for maturation of this fold, post-translational modifications of lasso peptides are rare. However, we recently delineated the biosynthetic pathway of a post-translationally phosphorylated lasso peptide, paeninodin. In this study, further investigation of two kinases revealed their ability to transfer multiple phosphate groups onto precursor peptide substrates, ultimately leading to polyphosphorylated lasso peptides. We found that this polyphosphorylating activity depended on the identity of the phosphate donor and the sequence of the precursor peptide. Our investigations provide new insight into the remarkable strategies for chemical diversification employed by the lasso peptide biosynthetic machinery.