Proteomic Analysis of Skin Defensive Factors of Tree Frog Hyla simplex

Abstract

Tree frogs produce a variety of skin defensive chemicals against many biotic and abiotic risk factors for their everyday survival. By proteomics or peptidomics and coupling transcriptome analysis with pharmacological testings, 27 peptides or proteins belonging to 9 families, which act mainly as defensive functions, were identified and characterized from skin secretions of the tree frog, Hyla simplex. They are: (1) a novel family of peptides with EGF- and VEGF-releasing activities; (2) a novel family of analgesic peptides; (3) a family of neurotoxins acting on sodium channel; (4) a snake venom-like presynaptically active neurotoxin; (5) a snake venom-like neurotoxin targeting cyclic nucleotide-gated ion channels; (6) a tachykinin-like peptide, which is the first report from tree frogs; (7) two antimicrobial peptides; (8) a alpha-1-antitrypsin-like serpin; and (9) a wasp venom-like toxin with serine protease inhibitors activity. Families of 1, 2, 4, 5, and 8 proteins or peptides are first reported in amphibians. The chemical array in the tree frog skin shares some similarities with snake venoms. Most of these components in this tree frog help defend against predators, heal wounds, or attenuate suffering.

Proteomic analysis of the skin from Chinese fire-bellied newt and comparison to Chinese giant salamander

“…It has been reported that amphibian skin secretions have anti-inflammatory, antibacterial, and antioxidant functions, and promote wound healing (Konig et al, 2015;Xu and Lai, 2015). Until now, the studies on the transcriptome (Huang et al, 2016), antioxidant peptidomes (Yang et al, 2009) and secretomes (Thompson et al, 2007) and proteomes (Wu et al, 2011) of frog skin have made great progress. In this study, we generated proteomics data of the newt skin using two-dimensional electrophoresis and MALDI-TOF/MS, and compared the protein kinds and expression values in the newt and giant salamander skin.…”

Protease Inhibitors from Marine Venomous Animals and Their Counterparts in Terrestrial Venomous Animals

“…From Hyla simplex , two serine protease inhibitors were isolated (Table 1)—an alpha-1-antitrypsin-like serpin (hylaserpin-S1) and a wasp venom-like toxin (hylaserpin-S2) [77]. Hylaserpin-S2 precursor is composed by 83 amino acid residues, including a predicted signal peptide of 27 residues.…”

“…Hylaserpin-S1 is a much longer peptide, with 44 kDa, and is encoded by a 415-amino acid residues precursor, with a signal peptide of 23 amino acid residues. Hylaserpin-S1 inhibited both trypsin and chymotrypsin, whereas hylaserpin-S2 only inhibited trypsin, similarly to BSTI [72,77]. Moreover, hylaserpin-S2 had bacteriostatic effect against Gram-positive bacteria Bacillus subtilis , and hylaserpin-S1 displayed direct microorganism-killing abilities against B. subtilis , E. coli , and Candida albicans [77].…”

Elucidating Novel Bacterial Targets and Designing Unusual Antimicrobial Peptides: Two Faces of the Same Proteomic Coin

“…One of the key targets in sorting AMPs using peptidomics has recently been to study amphibian secretions, due to the relative ease with which they are extracted and also thanks to the large amounts peptides found. Amphibians also produce a wide variety of skin defensive compounds in response to different abiotic and biotic factors for their everyday survival, which makes them interesting study models [57]. Peptidomic investigation has led to the categorization of multiple AMPs in norepinephrine-stimulated skin secretions of three species of frogs from the Ranidae family, including Lithobates forreri, Hylarana luctuosa, and Hylarana signata [58].…”