Structural Landscape of Syanodin I Lasso Peptide

Area of Science:

• Structural Biology
• Biophysical Chemistry
• Mass Spectrometry

Background:

• Lasso peptides are a unique class of cyclic peptides with complex topologies.
• Understanding their intricate structures is crucial for elucidating their biological functions.
• Comprehensive structural characterization often requires a multi-technique approach.

Purpose of the Study:

• To perform a comprehensive structural elucidation of the lasso peptide syanodin I.
• To investigate the conformational dynamics and intramolecular interactions of syanodin I.
• To establish a workflow integrating solution- and gas-phase techniques for biomolecular analysis.

Main Methods:

• Combined solution Nuclear Magnetic Resonance (NMR), gas-phase hydrogen/deuterium back-exchange (HDbX)-trapped ion mobility spectrometry (TIMS), electron capture dissociation (ECD) mass spectrometry, quantum mechanical (QM) calculations, and molecular dynamics (MD) simulations.
• Utilized NMR and ECD MS/MS for structural confirmation and identification of key residues.
• Employed TIMS and HDX-MS for analyzing conformational states and solvent accessibility.

Main Results:

• Confirmed an entangled lasso structure with Gln13 as the plug residue.
• Identified Ala11 in proximity to the macrolactam ring and a salt bridge between the C-terminus and Gln13 side chain.
• Resolved distinct conformers and intramolecular interactions using HDbX-TIMS-MS, revealing insights into folded structures.

Conclusions:

• The integrated workflow provides a powerful framework for probing biomolecular conformational dynamics.
• The combination of solution-phase hydrogen/deuterium exchange (HDX) with ion mobility spectrometry-mass spectrometry (IMS-MS) offers significant structural insights.
• This study successfully characterized the complex structure and dynamics of syanodin I.