Peptide name : Aurein-2.5

Source/Organism : Green and golden bell frog

Linear/Cyclic : Linear

Chirality : Not found

Peptide length: 72

C-terminal modification: Linear

N-terminal modification : Amidation

Non-natural peptide information: None

Assay type : Not specified

Assay time : Not found

Activity : LC50 : 10-5 - 10-4 M

Cell line : Human tumour cell lines

Cancer type : Breast cancer

Other activity : Anti-bacterial activity

Amino acid composition bar chart :

Molecular mass : 8129.1073 Dalton

Aliphatic index : 0.906

Instability index : 44.2153

Hydrophobicity (GRAVY) : -0.475

Isoelectric point : 4.8954

Charge (pH 7) : -5.3869

Aromaticity : 0.069

Molar extinction coefficient (cysteine, cystine): (0, 0)

Hydrophobic/hydrophilic ratio : 0.89473684

hydrophobic moment : 0.2651

Missing amino acid : T,W,P,Y

Most occurring amino acid : E

Most occurring amino acid frequency : 12

Least occurring amino acid : M

Least occurring amino acid frequency : 1

Secondary structure fraction (Helix, Turn, Sheet): (0.4, 0.2, 0.3)

SMILES Notation: CC[C@H](C)[C@H](NC(=O)[C@H](CO)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CO)NC(=O)[C@@H](NC(=O)[C@H](CC(C)C)NC(=O)CNC(=O)[C@H](CC(C)C)NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](CC(C)C)NC(=O)[C@@H](NC(=O)[C@H](CC(C)C)NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CO)NC(=O)[C@H](CCCCN)NC(=O)[C@H](CCCCN)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](C)NC(=O)[C@@H](N)CCSC)C(C)C)C(C)C)C(=O)N[C@@H](CS)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CCCNC(=N)N)C(=O)N[C@@H](CCC(N)=O)C(=O)N[C@@H](CC(N)=O)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](CC(=O)O)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](CC(=O)O)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](CC(N)=O)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](C)C(=O)N[C@@H](C)C(=O)N[C@@H](CC(N)=O)C(=O)N[C@@H](Cc1c[nH]cn1)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](CCC(=O)O)C(=O)NCC(=O)N[C@@H](CO)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CCCNC(=N)N)C(=O)NCC(=O)N[C@@H](CC(C)C)C(=O)N[C@@H](Cc1ccccc1)C(=O)N[C@@H](CC(=O)O)C(=O)N[C@H](C(=O)N[C@H](C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CCCCN)C(=O)N[C@H](C(=O)N[C@H](C(=O)NCC(=O)N[C@@H](C)C(=O)N[C@@H](Cc1ccccc1)C(=O)NCC(=O)N[C@@H](CO)C(=O)N[C@@H](CC(C)C)C(=O)NCC(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CCCNC(=N)N)C(=O)N[C@@H](CC(N)=O)C(=O)N[C@@H](CC(=O)O)C(=O)N[C@@H](CC(C)C)C(=O)N[C@@H](CCC(=O)O)C(=O)O)C(C)C)C(C)C)C(C)C)[C@@H](C)CC

1 : Chen T, et al. The structural organization of aurein precursor cDNAs from the skin secretion of the Australian green and golden bell frog, Litoria aurea. Regul Pept. 2005; 128:75-83. doi: 10.1016/j.regpep.2004.12.022

2 : Dennison SR, et al. The interaction of aurein 2.5 with fungal membranes. Eur Biophys J. 2014; 43:255-64. doi: 10.1007/s00249-014-0959-8

3 : Rozek T, et al. The antibiotic and anticancer active aurein peptides from the Australian Bell Frogs Litoria aurea and Litoria raniformis the solution structure of aurein 1.2. Eur J Biochem. 2000; 267:5330-41. doi: 10.1046/j.1432-1327.2000.01536.x

4 : Dennison SR, et al. Effect of amidation on the antimicrobial peptide aurein 2.5 from Australian southern bell frogs. Protein Pept Lett. 2012; 19:586-91. doi: 10.2174/092986612800494110

5 : Dennison SR, et al. A study on the interactions of Aurein 2.5 with bacterial membranes. Colloids Surf B Biointerfaces. 2009; 68:225-30. doi: 10.1016/j.colsurfb.2008.10.007

6 : Dennison SR, et al. Antimicrobial activity of aurein 2.5 against yeasts. FEMS Microbiol Lett. 2013; 346:140-5. doi: 10.1111/1574-6968.12212

7 : Ehrlich F, et al. Comparative genomics suggests loss of keratin K24 in three evolutionary lineages of mammals. Sci Rep. 2019; 9:10924. doi: 10.1038/s41598-019-47422-y

Paper title : The structural organization of aurein precursor cDNAs from the skin secretion of the Australian green and golden bell frog, Litoria aurea.

Doi : https://doi.org/10.1016/j.regpep.2004.12.022

Abstract : Aureins are a family of peptides (13-25 residues), some of which possess potent antimicrobial and anti-cancer properties, which have been classified into 5 subgroups based upon primary structural similarities. They were originally isolated from the defensive skin secretions of the closely related Australian bell frogs, Litoria aurea and Litoria raniformis, and of the 23 aurein peptides identified, 10 are common to both species. Using a recently developed technique, we have constructed a cDNA library from the defensive secretion of the green and golden bell frog, L. aurea, and successfully cloned a range of aurein precursor transcripts containing entire open-reading frames. All open-reading frames consisted of a putative signal peptide and an acidic pro-region followed by a single copy of aurein. The deduced precursor structures for the most active aureins (2.2 and 3.1) confirmed the presence of a C-terminal amidation motif whereas that of aurein 5.3 did not. Processed peptides corresponding in molecular mass to aureins 2.2, 2.3, 2.5, 3.1 and 5.3 were identified in the same secretion sample using LC/MS. The application of this technique thus permits parallel peptidomic and transcriptomic analyses on the same lyophilized skin secretion sample circumventing sacrifice of specimens of endangered herpetofauna.

Paper title : The interaction of aurein 2.5 with fungal membranes.

Doi : https://doi.org/10.1007/s00249-014-0959-8

Abstract : Aurein 2.5 (GLFDIVKKVVGAFGSL-NH2) is an antimicrobial peptide, which was seen to have activity against Stachybotris chartarum, Penicillium roseopurpureum and Aspergillus flavus with minimum fungicidal concentrations in the range 250-500 μM. S. chartarum showed enhanced susceptibility to lysis as compared to P. roseopurpureum and A. flavus, (44, 26 and 28 % respectively). Monolayers formed from lipid membrane extracts derived from S. chartarum, P. roseopurpureum and A. flavus showed maximal surface pressure changes of 13.5, 10.3 and 10.2 mN m(-1) respectively. However, aurein 2.5 adopted similar levels of α-helical structure (circa 45 %) in the presence of vesicles formed from membrane lipid extracts derived from all three fungi. These data imply that differential activity is not due to targeting and membrane association but linked to the ability of the bound peptide to lyse the cells. At sterol levels mimetic of eukaryotic systems, high levels of α-helical structure (circa 50 %) were also observed and hence similar binding. However, enhanced sterol levels (>0.6) led to a reduction in monolayer membrane interaction, suggesting that the sterols influence efficacy. Consistent with this suggestion, thermodynamic analysis showed that the peptide was able to destabilise model fungal monolayers, as indicated by negative values of ∆Gmix.

Paper title : The antibiotic and anticancer active aurein peptides from the Australian Bell Frogs Litoria aurea and Litoria raniformis the solution structure of aurein 1.2.

Doi : https://doi.org/10.1046/j.1432-1327.2000.01536.x

Abstract : Seventeen aurein peptides are present in the secretion from the granular dorsal glands of the Green and Golden Bell Frog Litoria aurea, and 16 from the corresponding secretion of the related Southern Bell Frog L. raniformis. Ten of these peptides are common to both species. Thirteen of the aurein peptides show wide-spectrum antibiotic and anticancer activity. These peptides are named in three groups (aureins 1-3) according to their sequences. Amongst the more active peptides are aurein 1.2 (GLFDIIKKIAESF-NH2), aurein 2.2 (GLFDIVKKVVGALGSL-NH2) and aurein 3.1 (GLFDIVKKIAGHIAGSI-NH2). Both L. aurea and L. raniformis have endoproteases that deactivate the major membrane-active aurein peptides by removing residues from both the N- and C-termini of the peptides. The most abundant degradation products have two residues missing from the N-terminal end of the peptide. The solution structure of the basic peptide, aurein 1.2, has been determined by NMR spectroscopy to be an amphipathic alpha-helix with well-defined hydrophilic and hydrophobic regions. Certain of the aurein peptides (e.g. aureins 1.2 and 3.1) show anticancer activity in the NCI test regime, with LC50 values in the 10-5-10-4 M range. The aurein 1 peptides have only 13 amino-acid residues: these are the smallest antibiotic and anticancer active peptides yet reported from an anuran. The longer aurein 4 and 5 peptides, e.g. aurein 4.1 (GLIQTIKEKLKELAGGLVTGIQS-OH) and aurein 5. 1 (GLLDIVTGLLGNLIVDVLKPKTPAS-OH) show neither antibacterial nor anticancer activity.

Paper title : Effect of amidation on the antimicrobial peptide aurein 2.5 from Australian southern bell frogs.

Doi : https://doi.org/10.2174/092986612800494110

Abstract : Aurein 2.5 is a naturally C-terminally amidated amphibian antimicrobial peptide. C-terminal amidation can increase efficacy and hence a comparison was made between aurein 2.5-CONH2 and its nonamidated analogue. Amidation of the C-terminal carboxyl of aurein 2.5 enhanced antimicrobial activity 2.5- fold against Klebsiella pneumonia. Our results demonstrate that both peptide analogues had high surface activities (23 mN m-1for aurein 2.5-COOH and 26 mN m-1 aurein 2.5-CONH2). Circular dichroism measurements suggest that the helical content of the amidated form, in the presence of trifluoroethanol, was significantly enhanced (33.66 % for aurein 2.5-COOH and 60.89 % aurein 2.5-CONH2). The interaction of aurein 2.5 with bacterial cell membrane mimics was investigated using Langmuir monolayers. Aurein 2.5-CONH2 induced stable surface pressure changes in monolayers formed from K. pneumonia (circa 4.7 mN m-1), however, lower surface pressure changes were observed for aurein 2.5- COOH (circa 3.8 mN m-1). The data shows that in the case of aurein 2.5, amidation is able to enhance antibacterial activity and it is proposed that the increase in effectiveness is due to stabilization of the α-helical structure at the membrane interface.

Paper title : A study on the interactions of Aurein 2.5 with bacterial membranes.

Doi : https://doi.org/10.1016/j.colsurfb.2008.10.007

Abstract : Aurein 2.5 (GLFDIVKKVVGAFGSL-NH(2)) is an uncharacterised antimicrobial peptide. At an air/water interface, it exhibited strong surface activity (maximal surface pressure 25mNm(-1)) and molecular areas consistent with the adoption of alpha-helical structure orientated either perpendicular (1.72nm(2)molecule(-1)) or parallel (3.6nm(2)molecule(-1)) to the interface. Aurein 2.5 was strongly antibacterial, exhibiting a minimum inhibitory concentration (MIC) of 30microM against Bacillus subtilis and Escherichia coli. The peptide induced maximal surface pressure changes of 9mNm(-1) and 5mNm(-1), respectively, in monolayers mimicking membranes of these organisms whilst compression isotherm analysis of these monolayers showed DeltaG(Mix)>0, indicating destabilisation by Aurein 2.5. These combined data suggested that toxicity of the peptide to these organisms may involve membrane invasion via the use of oblique orientated alpha-helical structure. The peptide induced strong, comparable maximal surface changes in monolayers of DOPG (7.5mNm(-1)) and DOPE monolayers (6mNm(-1)) suggesting that the membrane interactions of Aurein 2.5 were driven by amphiphilicity rather than electrostatic interaction. Based on these data, it was suggested that the differing ability of Aurein 2.5 to insert into membranes of B. subtilis and E. coli was probably related to membrane-based factors such as differences in lipid packing characteristics. The peptide was active against both sessile E. coli and Staphylococcus aureus with an MIC of 125microM. The broad-spectrum antibacterial activity and non-specific modes of membrane action used by Aurein 2.5 suggested use as an anti-biofilm agent such as in the decontamination of medical devices.

Paper title : Antimicrobial activity of aurein 2.5 against yeasts.

Doi : https://doi.org/10.1111/1574-6968.12212

Abstract : Fungal infections with multiple resistance to conventional antifungals are increasingly becoming a medical problem, and there is an urgent need for new antifungal compounds with novel mechanisms of action. Here, we show that aurein 2.5, a naturally occurring peptide antibiotic, displays activity against the fungal strains: Rhodotorula rubra and Schizosaccharomyces pombe (MICs < 130 μM). The peptide adopted high levels of membrane-interactive α-helical structure (> 65%) in the presence of lipid membranes derived from these organisms and showed strong propensities to penetrate (π ≥ 13 mN m(-1) ) and lyse them (> 70%). Based on these data, we suggest that aurein 2.5 kills yeasts via membranolytic mechanisms and may act as a template for the development of therapeutically useful antifungal agents.

Paper title : Comparative genomics suggests loss of keratin K24 in three evolutionary lineages of mammals.

Doi : https://doi.org/10.1038/s41598-019-47422-y

Abstract : Keratins are the main cytoskeletal proteins of epithelial cells and changes in the expression of keratins have contributed to the evolutionary adaptation of epithelia to different environments. Keratin K24 was proposed to be a differentiation marker of epidermal keratinocytes but the significance of K24 expression in the epidermis versus other tissues has remained elusive. Here, we show by RT-PCR, western blot, and immunofluorescence analyses that K24 is highly expressed in the epithelium of the cornea whereas its expression levels are significantly lower in other stratified epithelia including in the epidermis. To investigate the evolutionary history of K24, we screened the genome sequences of vertebrates for orthologs of the human KRT24 gene. The results of this comparative genomics study suggested that KRT24 originated in a common ancestor of amniotes and that it was lost independently in three clades of mammals, i.e. camels, cetaceans, and a subclade of pinnipeds comprising eared seals and the walrus. Together, the results of this study identify K24 as component of the cytoskeleton in the human corneal epithelium and reveal previously unknown differences of keratin gene content among mammalian species.