Identification and bioactivities evaluation of an antimicrobial peptide, QUB-2664, from the skin secretion of the Hainan odorous frog, Odorrana hainanensis

Abstract

The emergence of antibiotic-resistant clinical bacterial strains has driven many studies to focus on the antimicrobial molecules. Among them, antimicrobial peptides (AMPs) are a promising group because they have a unique bactericidal mechanism compared to antibiotics. Therefore, it is difficult for multidrug-resistant bacteria to develop resistance to AMPs. In this thesis, a peptide QUB-2664 belonging to the brevinin-1 family was identified from the skin secretions of Hainan stink frogs, Odorrana hainanensis. DNA-encoded biosynthetic precursors were primarily successfully cloned, followed by ‘shotgun’ cloning to deduce the mature peptide sequence. Subsequently, a series of techniques (SPPS, HPLC, and MALDI-TOF) was used to synthesise, purify, and identify the target peptide. Afterwards, QUB-2664 was subjected to several functional tests, including antibacterial, antifungal, antiproliferative and haemolytic assays.

The results revealed the mature peptide sequence as follows: FLPLIASLAANFVPKIFCKITKKC. The peptide exhibited potent antimicrobial activity against Klebsiella pneumoniae ATCC 43816, MRSA NCTC 12493, and Candida albicans ATCC CRM 10231, with MIC/MBC of 8/8, 4/8, and 32/32 µM, respectively. Meanwhile, it showed high haemolytic activity against equine erythrocytes at 512 µM. In addition, it exhibited low cytotoxicity against several cancer cell lines, especially lung cancer cell H838. It is expected that this study will provide opportunities for the discovery and design of new antimicrobial agents.

Thesis is embargoed until 31 December 2029.

Date of Award	Dec 2024
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Lei Wang (Supervisor), Tianbao Chen (Supervisor) & Mei Zhou (Supervisor)