5ua8
Ocellatin-F1, solution structure in SDS micelle by NMR spectroscopy
Structural highlights
FunctionOCEF1_LEPLB Antibacterial peptide that inhibits reference strains of both Gram-negative bacteria (E.coli, P.aeruginosa, E.cloacae, K.pneumoniae, and A.actinomycetemcomitans) and Gram-positive bacteria (S.aureus) with relatively low potencies (MIC=25-400 uM) (By similarity) (PubMed:28115922). Shows antifungal activity against C.lusitaniae (MIC=50.25 uM), but no activity against C.albicans (PubMed:28115922). In the presence of an alkaloid (bufotenine), inhibits cellular infection by the rabies virus (PubMed:26635873). The peptide shows very low hemolytic activity against rabbit erythrocytes (By similarity) (PubMed:28115922). The low amphipathicity of alpha-helices demonstrated by wheel projection as well as the low cationicity may explain the low antibacterial and hemolytic potencies (By similarity).[UniProtKB:P0DQJ8][1] [2] Publication Abstract from PubMedThe peptides ocellatin-LB1, -LB2 and -F1 have previously been isolated from anurans of the Leptodactylus genus and the sequences are identical from residue 1-22, which correspond to ocellatin-LB1 sequence (GVVDILKGAAKDIAGHLASKVM-NH2), whereas ocellatin-LB2 carries an extra N and ocellatin-F1 extra NKL residues at their C-termini. These peptides showed different spectra of activities and biophysical investigations indicated a direct correlation between membrane-disruptive properties and antimicrobial activities, i.e. ocellatin-F1>ocellatin-LB1>ocellatin-LB2. To better characterize their membrane interactions, we report here the detailed three-dimensional NMR structures of these peptides in TFE-d2:H2O (60:40) and in the presence of zwitterionic DPC-d38 and anionic SDS-d25 micellar solutions. Although the three peptides showed significant helical contents in the three mimetic environments, structural differences were noticed. When the structures of the three peptides in the presence of DPC-d38 micelles are compared to each other, a more pronounced curvature is observed for ocellatin-F1 and the bent helix, with the concave face composed mostly of hydrophobic residues, is consistent with the micellar curvature and the amphipathic nature of the molecule. Interestingly, an almost linear helical segment was observed for ocellatin-F1 in the presence of SDS-d25 micelles and the conformational differences in the two micellar environments are possibly related to the presence of the extra Lys residue near the peptide C-terminus, which increases the affinity of ocellatin-F1 to anionic membranes in comparison with ocellatin-LB1 and -LB2, as proved by isothermal titration calorimetry. To our knowledge, this work reports for the first time the three-dimensional structures of ocellatin peptides. NMR structures in different membrane environments of three ocellatin peptides isolated from Leptodactylus labyrinthicus.,Gomes KAGG, Dos Santos DM, Santos VM, Pilo-Veloso D, Mundim HM, Rodrigues LV, Liao LM, Verly RM, de Lima ME, Resende JM Peptides. 2018 Mar 26;103:72-83. doi: 10.1016/j.peptides.2018.03.016. PMID:29596881[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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