Paralithocins, Antimicrobial Peptides with Unusual Disulfide Connectivity from the Red King Crab, Paralithodes camtschaticus

• Published in: Journal of Natural Products
• Main Authors: Moe, Morten Kaare, Haug, Tor, Sydnes, Magne Olav, Sperstad, Sigmund, Li, Chun, Vaagsfjord, Lena Christine, de la Vega, Enrique, Stensvåg, Klara
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Chemical Society 2018
• Subjects: VDP::Mathematics and natural science: 400::Chemistry: 440; VDP::Matematikk og Naturvitenskap: 400::Kjemi: 440; Haug; Moe; Sperstad; Arctic; Paralithodes camtschaticus; Red king crab
• Online Access: https://hdl.handle.net/10037/14468; https://doi.org/10.1021/acs.jnatprod.7b00780

Submitted manuscript version. Published version available at https://doi.org/10.1021/acs.jnatprod.7b00780 . With permission from Moe, M.K., Haug, T., Sydnes, M.O., Sperstad, S.V., Li, C., Vaagsfjord, L.C., . Stensvåg, K. (2018). Paralithocins, Antimicrobial Peptides with Unusual Disulfide Connectivity from the Red King Crab, Paralithodes camtschaticus . Journal of natural products, 81 (1), 140-150. Copyright 2018 American Chemical Society. As part of an ongoing exploration of marine invertebrates as a source of new antimicrobial peptides, hemocyte extracts from the red king crab, Paralithodes camtschaticus , were studied. Three cationic cysteine (Cys)-rich peptides, named paralithocins 1–3, were isolated by bioassay-guided purification, and their amino acid sequences determined by Edman degradation and expressed sequences tag analysis. Disulfide bond mapping was performed by high-resolution tandem mass spectrometry. The peptides (38–51 amino acids in length) share a unique Cys motif composed of eight Cys, forming four disulfide bridges with a bond connectivity of (Cys relative position) Cys1–Cys8, Cys2–Cys6, Cys3–Cys5, and Cys4–Cys7, a disulfide arrangement that has not been previously reported among antimicrobial peptides. Thus, paralithocins 1–3 may be assigned to a previously unknown family of antimicrobial peptides within the group of Cys-rich antimicrobial peptides. Although none of the isolated peptides displayed antimicrobial activity against the target strains Escherichia coli, Pseudomonas aeruginosa , or Staphylococcus aureus , they inhibited the growth of several marine bacterial strains with minimal inhibitory concentrations in the 12.5–100 μM range. These findings corroborate the hypothesis that marine organisms are a valuable source for discovering bioactive peptides with new structural motifs.