Identification and functional evaluation of a bioactive peptide QUB-1369 Secreted from the skin of The Common Frog (Rana Temporaria)

Abstract

Antimicrobial peptides (AMPs) are host defence peptides found abundantly in amphibian skin secretions. They have broad antimicrobial spectrum of Gram-positive bacteria, Gram-negative bacteria, fungi and viruses. In this study, skin secretion of the common frog, Rana temporaria, was used to build a cDNA library by mRNA transcription. A cDNA encoding a peptide biosynthetic precursor transcript was consistently cloned from this by “shot-gun” cloning. The precursor peptide sequence was analysed by bioinformatics tools such as NCBI-BLAST, while Uniprot identified the mature peptide sequence (FLPIVGKLLSGLL-NH2). Then, using Fmoc solid -phase peptide synthesis, the peptide chain was assembled stepwise and attached to resin support. After the peptide was assembled, it was removed from the resin to obtain a crude linear peptide. Reverse-phase HPLC was used to obtain a purified peptide and in accordance with its molecular mass obtained by MALDI-TOF MS, the peptide was named QUB-1369. Antimicrobial assays showed that QUB-1369 was active against Gram-positive bacterium, Staphylococcus aureus and the yeast, Candida albicans at concentrations of 8 µM and 128 µM, respectively. It was not active against Gram-negative bacterium, Escherichia coli. Haemolysis assay of QUB-1369 using horse erythrocytes, showed it was active at a concentration of 16 µM. Anticancer assay found a weak inhibition of HCT 116 Human Colon Carcinoma cells at a concentration of 100 µM.

Date of Award	Dec 2020
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Tianbao Chen (Supervisor), Mei Zhou (Supervisor), Lei Wang (Supervisor) & Xinping Xi (Supervisor)