The Significance of Hypervariability and Conserved Motifs in Antimicrobial Peptides from Tree Frogs

Abstract

Amphibians' skin is a rich source of natural antimicrobial peptides (AMPs). These AMPs exhibit marked inter-and intraspecific sequence divergence linked to the arms race between host and pathogens. Here, we combine peptidomics, molecular modeling, and phylogenetic analyses to understand the evolution of AMPs in Cophomantini, a diverse clade of neotropical tree frogs, and to investigate their interaction with bacterial membranes. Consistent with results in other amphibians, all species of Cophomantini secrete a mixture of peptides. We selected the hylin peptide family to survey sequence variability and the presence of common amino acid motifs. We found that most species secrete a unique set of hylins that, though variable, share the conserved motif Gly-X-X-X-Pro-Ala-X-X-Gly, with Gly and Pro colocalizing with charged or polar residues. Our modeling revealed that Pro curves the peptide through a hinge, facilitating its insertion into the bacterial membrane and, once inserted, contributes to stabilizing the pore structure. The phylogenetic inference using hylid prepropeptides showed the need to classify new AMPs using the full-length sequence of the prepro-peptide region and highlighted the complex relationships between peptide families. Our findings revealed that conserved motifs occurred independently in distinct AMP families, suggesting a convergent evolution and a significant role in peptide−membrane interactions.

A Comprehensive Review of Patented Antimicrobial Peptides from Amphibian Anurans

“…Upon stimulation or injury, a second endopeptidase cleaves the inactive peptide, activating the mature peptides (Figure ). , This transformation provides insights into the effectiveness of these peptides against pathogens. ,, …”

“…68,102−104 It has been described that the signal peptide (SP) is crucial for regulating the intracellular transport of the peptide, 102 and the propeptide region maintains the inactive form of the AMPs. 68,105 Both regions exhibit varying degrees of conservation, but they are much higher than the mature AMP, which has been widely described as the least conserved region within families of anuran AMPs. 102 The mature AMP carries out the biological activity of the peptide.…”

“…105,106 This transformation provides insights into the effectiveness of these peptides against pathogens. 68,104,106 Among the modifications of the mature sequences of the peptide described in the patents, we can find the following: modification of the carboxylic acid of the C-terminal with an 7). Lysine (K) has been coupled to fatty acids ranging from C10 to C20 or glycans at the amino group of the epsilon carbon.…”

“…68,105 Though a clear evolutionary understanding of AMPs is limited because of their short length and the hypervariability of the mature regions, some alternatives to overcome these problems include using the complete sequence of the peptides. 68,105 As reviewed in the literature among the main AMP families isolated from anurans, we can find bombinin, magainin, XPF, dermaseptin, brevinin, caerin, esculentin, ranalexin, rugosin, temporin, uperin, ranatuerin, maculatin, citropin, aurein, phylloxin, palustrin, kassinatuerin, tigerinin, pseudin, distinctin, nigrocin, dahlein, japonicin, ranacyclin, ocellatin, ascaphin, phylloseptin, lividin, pelophylaxin, dybowskin, pleurain, odorranain, hyposin, fallaxidin, nigroain, andersonin, cathelicidin, h y m e n o c h i r i n , f r e n a t i n , d e f e n s i n , a n d k a s s o rins. 30,31,[33][34][35][37][38][39][40][41][42]61,63,64,67,72 Additionally, this analysis includes other significant peptides isolated from anurans due to their biological significance (Table 2 and Supporting Information 1.2).…”

Influence of Fatty Acid Modification on the Anticancer Activity of the Antimicrobial Peptide Figainin 1

“…Antimicrobial peptides are generally cationic amphiphiles with a high content of hydrophobic residues. These properties enable them to interact with negatively charged cancer cell membranes, leading to cancer cell death, and lower the risk of the development of resistance . To date, three typical antimicrobial peptide membrane failure models have been proposed, including the barrel stave model, carpet model, and annular whole model. , In addition to membrane destruction, antimicrobial peptides may also have multiple other mechanisms.…”