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Identification of novel peptides from amphibian ( Xenopus tropicalis ) skin by direct tissue MALDI ‐ MS analysis
Author(s) -
Shigeri Yasushi,
Yasuda Akikazu,
Hagihara Yoshihisa,
Nishi Kaito,
Watanabe Kunihiko,
Imura Tomohiro,
Inagaki Hidetoshi,
Haramoto Yoshikazu,
Ito Yuzuru,
Asashima Makoto
Publication year - 2015
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.13107
Subject(s) - chemistry , biochemistry
Twelve novel peptides (Pxt‐1 to Pxt‐12) were isolated from the skin of Xenopus tropicalis , diploid frogs, using topological MS analysis. Among them, Pxt‐8, Pxt‐9, and Pxt‐10 were the N terminus of Pxt‐1, N terminus of Pxt‐3 and C terminus of Pxt‐11, respectively. The Pxt‐3 and Pxt‐11 peptides shared significant sequence homologies with magainins 1, ‐2 and levitide, respectively, which all isolated from X. laevis . Pxt‐12 was identical to the X. tropicalis XT ‐6‐like precursor previously isolated by ESI ‐ MS / MS . None of the Pxt peptides contained any Cys, Asp, Tyr or Trp, although Leu and Lys were frequently found as typical frog‐skin peptides. RT ‐ PCR analysis confirmed the gene expressions of Pxt‐2, Pxt‐3, Pxt‐4, Pxt‐5, Pxt‐7 and Pxt‐11 in X. tropicalis skin. Several ion peaks corresponding to all identified Pxt peptides were observed with MALDI ‐ MS analysis of X. tropicalis secretory fluids, collected after in vivo stimulation, which suggested that Pxt peptides were definitely secretory molecules. CD studies and Schiffer–Edmundson helical wheel projections suggested that Pxt‐5, as well as mastoparan, at least, could form a typical amphiphilic α helix without a phospholipid or a membrane‐mimetic solvent (trifluoroethanol). Moreover, Pxt‐2 and Pxt‐5 showed growth inhibitory effects on both Escherichia coli (Gram‐negative) and Staphylococcus aureus (Gram‐positive). Measurements of dynamic light scattering and the surface tensions of Pxt peptides solutions suggested that both Pxt‐2 and Pxt‐5 could form associations as micelles and behave like a general surfactant. Moreover, the remarkable foaming properties of Pxt‐2 and Pxt‐5 were observed, as well as those of the secretory fluids of X. tropicalis .