RNA isn’t the only biomolecule that can adopt lariat structures. Lasso peptides have their C-terminal tail directed through an N-terminal macrolactam ring, and these microbial natural products have gathered growing attention for their potential use in a variety of bioactive contexts. Herbert Nar and colleagues at Boehringer Ingelheim, Germany, determined the first high-resolution crystal structure of a lasso peptide known as BI-32169, providing unprecedented detail into the structure of this class of important natural products.

With the first crystal structure of a lasso peptide now in hand, analysis of the fine structure of the lasso fold at atomic resolution is possible, as are discussions of structural details in terms of the known biochemical properties of BI-32169 as a representative of this family of peptides.

• High-Resolution Crystal Structure of a Lasso Peptide
  H. Nar, A. Schmid, C. Puder, O. Potterat,
  ChemMedChem 2010, 5(10).
  http://dx.doi.org/10.1002/cmdc.201000264