Xanthomonins I-III: A New Class of Lasso Peptides with a Seven-Residue Macrolactam Ring.
Hegemann, J.D., Zimmermann, M., Zhu, S., Steuber, H., Harms, K., Xie, X., Marahiel, M.A.(2014) Angew Chem Int Ed Engl 53: 2230-2234
- PubMed: 24446383 
- DOI: https://doi.org/10.1002/anie.201309267
- Primary Citation of Related Structures:  
4NAG - PubMed Abstract: 
Lasso peptides belong to the class of ribosomally synthesized and post-translationally modified peptides. Their common distinguishing feature is an N-terminal macrolactam ring that is threaded by the C-terminal tail. This lasso fold is maintained through steric interactions. The isolation and characterization of xanthomonins I-III, the first lasso peptides featuring macrolactam rings consisting of only seven amino acids, is now presented. The crystal structure of xanthomonin I and the NMR structure of xanthomonin II were also determined. A total of 25 variants of xanthomonin II were generated to probe different aspects of the biosynthesis, stability, and fold maintenance. These mutational studies reveal the limits such a small ring imposes on the threading and show that every plug amino acid larger than serine is able to maintain a heat-stable lasso fold in the xanthomonin II scaffold.
Organizational Affiliation: 
Fachbereich Chemie, Fachgebiet Biochemie und LOEWE-Zentrum für Synthetische, Mikrobiologie, Philipps-Universität Marburg, Meerwein-Strasse 4, 35032 Marburg (Germany).