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Discovery of Novel Bacterial Cell-Penetrating Phylloseptins in Defensive Skin Secretions of the South American Hylid Frogs, Phyllomedusa duellmani and Phyllomedusa coelestis

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ABSTRACT

Phylloseptin (PS) peptides, derived from South American hylid frogs (subfamily Phyllomedusinae), have been found to have broad-spectrum antimicrobial activities and relatively low haemolytic activities. Although PS peptides have been identified from several well-known and widely-distributed species of the Phyllomedusinae, there remains merit in their study in additional, more obscure and specialised members of this taxon. Here, we report the discovery of two novel PS peptides, named PS-Du and PS-Co, which were respectively identified for the first time and isolated from the skin secretions of Phyllomedusa duellmani and Phyllomedusa coelestis. Their encoding cDNAs were cloned, from which it was possible to deduce the entire primary structures of their biosynthetic precursors. Reversed-phase high-performance liquid chromatography (RP-HPLC) and tandem mass spectrometry (MS/MS) analyses were employed to isolate and structurally-characterise respective encoded PS peptides from skin secretions. The peptides had molecular masses of 2049.7 Da (PS-Du) and 1972.8 Da (PS-Co). They shared typical N-terminal sequences and C-terminal amidation with other known phylloseptins. The two peptides exhibited growth inhibitory activity against E. coli (NCTC 10418), as a standard Gram-negative bacterium, S. aureus (NCTC 10788), as a standard Gram-positive bacterium and C. albicans (NCPF 1467), as a standard pathogenic yeast, all as planktonic cultures. Moreover, both peptides demonstrated the capability of eliminating S. aureus biofilm.

No MeSH data available.


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Minimal inhibitory concentration (MIC) curves obtained following incubation of C. albicans, E. coli, and S. aureus with the natural peptides, PS-Du (A), PS-Co (B) and the structurally-modified peptides, PS-Du K7H (C) and PS-Co K7H (D) at concentrations ranging from 512 mg/L to 1 mg/L. The blank control was established by culture medium and the positive control was represented by growth culture. Data represent means ± SEM (standard error of the mean) of 5 replicates.
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toxins-08-00255-f009: Minimal inhibitory concentration (MIC) curves obtained following incubation of C. albicans, E. coli, and S. aureus with the natural peptides, PS-Du (A), PS-Co (B) and the structurally-modified peptides, PS-Du K7H (C) and PS-Co K7H (D) at concentrations ranging from 512 mg/L to 1 mg/L. The blank control was established by culture medium and the positive control was represented by growth culture. Data represent means ± SEM (standard error of the mean) of 5 replicates.

Mentions: Synthetic PS-Du and PS-Co and their respective structurally-modified analogues, PS-Du K7H and PS-Co K7H, exhibited growth inhibitory activity against the Gram-positive bacterium, S. aureus, the Gram-negative bacterium, E. coli and the potentially-pathogenic yeast, C. albicans. MICs (minimal inhibitory concentrations)of all four peptides are summarised in Table 1 and MIC curves are shown in Figure 9. The skin secretion-derived peptides, PS-Du and PS-Co, showed similar potencies with MIC values of 8 mg/L against S. aureus, 128 mg/L against E. coli and 16 mg/L against C. albicans. The modified peptide analogues, PS-Du K7H and PS-Co K7H, showed similar inhibition with MIC values of 32 mg/L towards S. aureus, 512 mg/L towards E. coli and 64 mg/L towards C. albicans. Both natural peptides, PS-Du and PS-Co, and modified peptides, PS-Du K7H and PS-Co K7H, exhibited moderate haemolytic effects on horse red blood cells as shown in Figure 10.


Discovery of Novel Bacterial Cell-Penetrating Phylloseptins in Defensive Skin Secretions of the South American Hylid Frogs, Phyllomedusa duellmani and Phyllomedusa coelestis
Minimal inhibitory concentration (MIC) curves obtained following incubation of C. albicans, E. coli, and S. aureus with the natural peptides, PS-Du (A), PS-Co (B) and the structurally-modified peptides, PS-Du K7H (C) and PS-Co K7H (D) at concentrations ranging from 512 mg/L to 1 mg/L. The blank control was established by culture medium and the positive control was represented by growth culture. Data represent means ± SEM (standard error of the mean) of 5 replicates.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037481&req=5

toxins-08-00255-f009: Minimal inhibitory concentration (MIC) curves obtained following incubation of C. albicans, E. coli, and S. aureus with the natural peptides, PS-Du (A), PS-Co (B) and the structurally-modified peptides, PS-Du K7H (C) and PS-Co K7H (D) at concentrations ranging from 512 mg/L to 1 mg/L. The blank control was established by culture medium and the positive control was represented by growth culture. Data represent means ± SEM (standard error of the mean) of 5 replicates.
Mentions: Synthetic PS-Du and PS-Co and their respective structurally-modified analogues, PS-Du K7H and PS-Co K7H, exhibited growth inhibitory activity against the Gram-positive bacterium, S. aureus, the Gram-negative bacterium, E. coli and the potentially-pathogenic yeast, C. albicans. MICs (minimal inhibitory concentrations)of all four peptides are summarised in Table 1 and MIC curves are shown in Figure 9. The skin secretion-derived peptides, PS-Du and PS-Co, showed similar potencies with MIC values of 8 mg/L against S. aureus, 128 mg/L against E. coli and 16 mg/L against C. albicans. The modified peptide analogues, PS-Du K7H and PS-Co K7H, showed similar inhibition with MIC values of 32 mg/L towards S. aureus, 512 mg/L towards E. coli and 64 mg/L towards C. albicans. Both natural peptides, PS-Du and PS-Co, and modified peptides, PS-Du K7H and PS-Co K7H, exhibited moderate haemolytic effects on horse red blood cells as shown in Figure 10.

View Article: PubMed Central - PubMed

ABSTRACT

Phylloseptin (PS) peptides, derived from South American hylid frogs (subfamily Phyllomedusinae), have been found to have broad-spectrum antimicrobial activities and relatively low haemolytic activities. Although PS peptides have been identified from several well-known and widely-distributed species of the Phyllomedusinae, there remains merit in their study in additional, more obscure and specialised members of this taxon. Here, we report the discovery of two novel PS peptides, named PS-Du and PS-Co, which were respectively identified for the first time and isolated from the skin secretions of Phyllomedusa duellmani and Phyllomedusa coelestis. Their encoding cDNAs were cloned, from which it was possible to deduce the entire primary structures of their biosynthetic precursors. Reversed-phase high-performance liquid chromatography (RP-HPLC) and tandem mass spectrometry (MS/MS) analyses were employed to isolate and structurally-characterise respective encoded PS peptides from skin secretions. The peptides had molecular masses of 2049.7 Da (PS-Du) and 1972.8 Da (PS-Co). They shared typical N-terminal sequences and C-terminal amidation with other known phylloseptins. The two peptides exhibited growth inhibitory activity against E. coli (NCTC 10418), as a standard Gram-negative bacterium, S. aureus (NCTC 10788), as a standard Gram-positive bacterium and C. albicans (NCPF 1467), as a standard pathogenic yeast, all as planktonic cultures. Moreover, both peptides demonstrated the capability of eliminating S. aureus biofilm.

No MeSH data available.


Related in: MedlinePlus