P23 Halogenated antimicrobial peptides from the red sea urchin Echinus esculentus

P23 Halogenated antimicrobial peptides from the red sea urchin Echinus esculentus

Tor Haug1, Runar Gjerp Solstad2, Chun Li1, Johan Isaksson3, Jostein Johansen3, Johan Svenson4 and Klara Stensvåg1

1The Norwegian College Of Fishery Science, Faculty Of Biosciences, Fisheries And Economics, Uit The Arctic University Of Norway, Tromsø, NOR
2Nofima AS, Tromsø, NOR
3Department Of Chemistry, Faculty Of Science And Technology, Uit The Arctic University Of Norway, Tromsø, NOR
4Department Of Chemistry, Materials And Surfaces SP Technical Research Institute Of Sweden, Borås, SWE

Natural antimicrobial peptides (AMPs) are considered promising candidates for drug development. This study aimed to isolate and characterize AMPs from the coelomocytes of the sea urchin Echinus esculentus. Using bioassay-guided purification and cDNA cloning, three AMPs were characterized; two heterodimeric peptides (EeCentrocin 1 and 2) and a cysteine-rich peptide (EeStrongylocin 2). The EeCentrocins (4.6-4.8 kDa) are intramolecularly connected via a disulphide bond to form heterodimeric structures, containing a cationic heavy chain of 30-32 amino acids and a light chain of 13 amino acids. The heavy chains of the EeCentrocins were synthesized and shown to be responsible for the antimicrobial activity of the natural peptides. EeStrongylocin 2 (5.9 kDa) contains 51 residues, where 6 cysteines are engaged in 3 disulphide bonds. Using mass spectrometric and NMR analyses, EeCentrocins 1 and 2, and EeStrongylocin 2 were all shown to contain post-translationally brominated tryptophan residues - in position 6 of the indole ring.