![]() ![]() However, additional sampling, especially among the largely poorly sampled non-neobatrachian lineages, is required to confirm this hypothesis and could reveal the existence of additional signal sequence motifs. Together with the lack of a linear relationship between the degree of sequence divergence and evolutionary time, we hypothesize that the anuran AMP system has evolved convergently on at least three occasions. The signal sequences are strongly conserved within each lineage (as previously noted for Neobatrachia), but highly divergent between them. Comparison of cDNA sequences suggests that there are at least three different motifs within the signal peptide sequence of the AMP-precursor corresponding to the evolutionary lineages Neobatrachia, Bombinatoridae (Bombina spp.) and Pipidae (Xenopus laevis). Here, we analyze the DNA information for the signal sequences of the AMP precursors in anuran amphibians available to the end of 2009 in an explicit phylogenetic framework to characterize the evolution of this large, diverse gene family. To date, DNA sequence information regarding AMP genes in anurans is restricted to only a few anuran families and largely to & amp amp amp amp amp quot higher frogs& amp amp amp amp amp quot (Neobatrachia). aureus (MRSA) and multidrug-resistant Acinetobacter baumannii (MDRAB) with MIC values in the range 4–8 μM.Īmphibians are characterized in part by their highly specialized and glandular skin that enables key physiological functions such as cutaneous respiration and defense against a variety of micro- and macroscopic predators via toxic components (e.g., alkaloids and bufodienolids), biogenic amines, neuropeptides and antimicrobial peptides (AMPs). CPF-B1 was active against clinical isolates of the nosocomial pathogens, methicillin-resistant S. This peptide was also the most abundant antimicrobial peptide in the skin secretions. ![]() aureus, and MIC = 25 μM against Candida albicans, and low hemolytic activity against human erythrocytes (LC50 > 200 μM). The peptide with the greatest potential for development into a therapeutically valuable anti-infective agent was CPF-B1 (GLGSLLGKAFKIGLKTVGKMMGGAPREQ) with MIC = 5 μM against E. terminal glycine and carboxy terminal leucinamide), caerulein precursor fragment, and xenopsin precursor fragment (Soravia et al., 1988 Giovannini et al. In addition, a second magainin-related peptide (G**KFLHSAGKFGKAFLGEVMIG) containing a two amino acid residue deletion compared with magainin-2 was identified that had only weak antimicrobial activity. Structural characterization of the peptides demonstrated that they were orthologous to magainin-2 (1 peptide), peptide glycine–leucine-amide, PGLa (2 peptides), caerulein-precursor fragments, CPF (4 peptides), and xenopsin-precursor fragments, XPF (2 peptides), previously isolated from Xenopus laevis and X. The data indicate, therefore, that nonfunctionalization (gene deletion) has been the most common fate of duplicated antimicrobial peptide genes following polyploidization events in the Silurana and Xenopus lineages.Nine peptides with differential growth inhibitory activity against Escherichia coli and Staphylococcus aureus were isolated from norepinephrine-stimulated skin secretions of the tetraploid frog Xenopus borealis Parker, 1936 (Pipidae). borealis, and five from the tetraploid frog X. tropicalis, nine from the tetraploid frog X. Under the same experimental conditions, seven orthologous antimicrobial peptides were previously isolated from the diploid frog S. andrei components comprised two peptides from the magainin family, (magainin-AN1 and -AN2), two from the XPF family (XPF-AN1 and -AN2), two from the PGLa family(PGLa-AN1 and -AN2), and one caerulein-precursor fragment (CPF-AN1).The primary structures of these peptides indicate a close phylogenetic relationship between X. The CPF peptides showed potent, broad-spectrum antimicrobial activity. paratropicalis components comprised three peptides belonging to the caerulein-precursor fragment family (CPF-SP1, -SP2 and -SP3), two peptides from the xenopsin-precursor fragment family (XPF-SP1 and -SP2), and one peptide orthologous to peptide glycine-leucine-amide (PGLa-SP1). Structural characterization demonstrated that the S. andrei led to identification of multiple peptides with growth-inhibitory activity against Escherichia coli and Staphylococcus aureus. Peptidomic analysis of norepinephrine-stimulated skin secretions of S. paratropicalis and a second polyploidization within the Xenopus lineage has produced the octoploid frog X. A putative genome duplication event within the Silurana lineage has given rise to the tetraploid frog S. ![]()
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