Amino acid tailoring strategies in peptide natural product biosynthesis

Recently characterized outstanding examples of noncanonical amino acid biosynthesis sequences in modified peptide natural product biosynthetic pathways are reviewed. Enzymatic modifications can occur on single precursors, enzyme-bound intermediates, or post assembly for nonribosomal systems or on precursor peptides for ribosomal systems. Different examples of convergent evolution and cooperation of biosynthetic systems were uncovered. Modified peptide natural products are renowned for their exceptional structural diversity, which translates into a broad spectrum of bioactivities and therapeutic potential. For their biosynthesis, nature has evolved two fundamentally different strategies – through a ribosomal and a nonribosomal route. Pivotal to the peptides’ structural diversity are their underlining amino acid building blocks, often transformed by specialized biosynthetic enzymes into noncanonical residues, frequently crucial for their bioactivities. In this review, we highlight recent advances in deciphering the biosynthesis of unusual and highly modified amino acids across peptide natural product biosynthetic pathways. We introduce different tailoring routes that may lead to similar or even the same products and outline unexpected combinations of pathway types discovered to produce complex chemistry. Modified peptide natural products are renowned for their exceptional structural diversity, which translates into a broad spectrum of bioactivities and therapeutic potential. For their biosynthesis, nature has evolved two fundamentally different strategies – through a ribosomal and a nonribosomal route. Pivotal to the peptides’ structural diversity are their underlining amino acid building blocks, often transformed by specialized biosynthetic enzymes into noncanonical residues, frequently crucial for their bioactivities. In this review, we highlight recent advances in deciphering the biosynthesis of unusual and highly modified amino acids across peptide natural product biosynthetic pathways. We introduce different tailoring routes that may lead to similar or even the same products and outline unexpected combinations of pathway types discovered to produce complex chemistry.