(408b) Towards Understanding Lasso Peptide Biosynthesis and Regulation Through Genome-Mining

Lasso peptides are a growing class of ribosomally-synthesized and posttranslationally modified peptides (RiPPs) that are folded into a structure resembling a threaded lasso.  This class of molecules shares a conserved gene cluster architecture that includes an exporter protein in addition to the maturation enzymes that tailor the gene-encoded polypeptide precursor into the lasso form.  Using conserved elements in the precursor peptide and the maturation enzymes, we developed a genome mining approach that identified 79 putative lasso peptide biosynthesis clusters in a broad range of bacterial phyla (1).  We have experimentally validated two of these clusters by expressing and characterizing three novel lasso peptides encoded by them and solved the structures of two of them by NMR.  We present these results and our findings regarding the heterologous expression and purification of these molecules.  Additionally, the gene architectures of these clusters deviate from the typical lasso peptide architecture by having a predicted protease instead of a transporter protein.  We have experimentally characterized this enzyme and applied a bioinformatics approach to re-examine lasso peptide gene cluster architectures in light of this discovery. 

1. Maksimov MO, Pelczer I, & Link AJ (2012) Precursor-centric genome-mining approach for lasso peptide discovery. Proceedings of the National Academy of Sciences 109(38):15223-15228.