Title
Towards mapping electrostatic interactions between Kdo2-lipid A and cationic antimicrobial peptides viaultraviolet photodissociation mass spectrometry
Author
Christopher M. Crittenden, Lindsay J. Morrison, Mignon D. Fitzpatrick, Allison P. Myers, Elisa T. Novelli, Jake Rosenberg, Lucas D. Akin, Vishnu Srinivasa, Jason B. Shear, Jennifer S. Brodbelt
Year
2018
Journal
Analyst
Abstract
Cationic antimicrobial peptides (CAMPs) have been known to act as multi-modal weapons against Gram-negative bacteria. As a new approach to investigate the nature of the interactions between CAMPs and the surfaces of bacteria, native mass spectrometry and two MS/MS strategies (ultraviolet photodissociation (UVPD) and higher energy collisional activation (HCD)) are used to examine formation and disassembly of saccharolipid·peptide complexes. Kdo2-lipid A (KLA) is used as a model saccharolipid to evaluate complexation with a series of cationic peptides (melittin and three analogs). Collisional activation of the KLA·peptide complexes results in the disruption of electrostatic interactions, resulting in apo-sequence ions with shifts in the distribution of ions compared to the fragmentation patterns of the apo-peptides. UVPD of the KLA·peptide complexes results in both apo- and holo-sequence ions of the peptides, the latter in which the KLA remains bound to the truncated peptide fragment despite cleavage of a covalent bond of the peptide backbone. Mapping both the N- and C-terminal holo-product ions gives insight into the peptide motifs (specifically an electropositive KRKR segment and a proline residue) that are responsible for mediating the electrostatic interactions between the cationic peptides and saccharolipid.
Instrument
J-815
Keywords
Circular dichroism, Secondary structure, Vesicle interactions, Chemical stability, Biochemistry