Structural Insights from Tandem Mass Spectrometry, Ion Mobility-Mass Spectrometry, and Infrared/Ultraviolet Spectroscopy on Sphingonodin I: Lasso vs Branched-Cyclic Topoisomers.
Kevin Jeanne Dit FouqueValeriu ScutelnicJulian D HegemannSylvie RebuffatPhilippe MaîtreThomas R RizzoFrancisco Fernandez LimaPublished in: Journal of the American Society for Mass Spectrometry (2021)
Lasso peptides form a class of ribosomally synthesized and post-translationally modified peptides (RiPPs) characterized by a mechanically interlocked topology, where the C-terminal tail of the peptide is threaded and trapped within an N-terminal macrolactam ring. Sphingonodin I is a lasso peptide that has not yet been structurally characterized using the traditional structural biology tools (e.g., NMR and X-ray crystallography), and its biological function has not yet been elucidated. In the present work, we describe structural signatures characteristic of the class II lasso peptide sphingonodin I and its branched-cyclic analogue using a combination of gas-phase ion tools (e.g., tandem mass spectrometry, MS/MS, trapped ion mobility spectrometry, TIMS, and infrared, IR, and ultraviolet, UV, spectroscopies). Tandem MS/MS CID experiments on sphingonodin I yielded mechanically interlocked species with associated bi and yj fragments demonstrating the presence of a lasso topology, while tandem MS/MS ECD experiments on sphingonodin I showed a significant increase in hydrogen migration in the loop region when compared to the branched-cyclic analogue. The high-mobility resolving power of TIMS permitted the separation of both topoisomers, where sphingonodin I adopted a more compact structure than its branched-cyclic analogue. Cryogenic and room-temperature IR spectroscopy experiments evidenced a different hydrogen bond network between the two topologies, while cryogenic UV spectroscopy experiments clearly demonstrated a distinct phenylalanine environment for the lasso peptide.
Keyphrases
- tandem mass spectrometry
- high resolution
- ultra high performance liquid chromatography
- liquid chromatography
- high performance liquid chromatography
- ms ms
- mass spectrometry
- gas chromatography
- simultaneous determination
- room temperature
- solid phase extraction
- high resolution mass spectrometry
- liquid chromatography tandem mass spectrometry
- single molecule
- solid state
- capillary electrophoresis
- genome wide
- magnetic resonance
- dna methylation
- genetic diversity
- amino acid