Structure and Function of a Dehydrating Condensation Domain in Nonribosomal Peptide Biosynthesis.
Patteson, J.B., Fortinez, C.M., Putz, A.T., Rodriguez-Rivas, J., Bryant 3rd, L.H., Adhikari, K., Weigt, M., Schmeing, T.M., Li, B.(2022) J Am Chem Soc 144: 14057-14070
- PubMed: 35895935 
- DOI: https://doi.org/10.1021/jacs.1c13404
- Primary Citation of Related Structures:  
7R9X - PubMed Abstract: 
Dehydroamino acids are important structural motifs and biosynthetic intermediates for natural products. Many bioactive natural products of nonribosomal origin contain dehydroamino acids; however, the biosynthesis of dehydroamino acids in most nonribosomal peptides is not well understood. Here, we provide biochemical and bioinformatic evidence in support of the role of a unique class of condensation domains in dehydration (C modAA ). We also obtain the crystal structure of a C modAA domain, which is part of the nonribosomal peptide synthetase AmbE in the biosynthesis of the antibiotic methoxyvinylglycine. Biochemical analysis reveals that AmbE-C modAA modifies a peptide substrate that is attached to the donor carrier protein. Mutational studies of AmbE-C modAA identify several key residues for activity, including four residues that are mostly conserved in the C modAA subfamily. Alanine mutation of these conserved residues either significantly increases or decreases AmbE activity. AmbE exhibits a dimeric conformation, which is uncommon and could enable transfer of an intermediate between different protomers. Our discovery highlights a central dehydrating function for C modAA domains that unifies dehydroamino acid biosynthesis in diverse nonribosomal peptide pathways. Our work also begins to shed light on the mechanism of C modAA domains. Understanding C modAA domain function may facilitate identification of new natural products that contain dehydroamino acids and enable engineering of dehydroamino acids into nonribosomal peptides.
Organizational Affiliation: 
Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.