Lys17 in the 'lasso' peptide lariatin A is responsible for anti-mycobacterial activity

C-terminal-lacking fragments of the anti-mycobacterial peptide lariatin A were obtained by hydrolysis using carboxypeptidase P and their anti-mycobacterial activities were evaluated. Lys17 was found to be essential for their antimicrobial activity. A molecular dynamics simulation, with explicit water molecules, helped determine the structural characteristics of Lys17 of lariatin A. The simulation revealed the dynamic formation and deformation of a salt bridge between the N(xi) atom of Lys17 and the carboxyl group of C-terminal Pro18, which is deemed to be crucial for the compound's anti-mycobacterial activity.