Engineering Miniproteins and β-Hairpins for Anticancer and Antimicrobial Applications

Abstract

Targeted drug delivery systems for cancer therapy are rapidly advancing, but the availability of efficient targeting ligands remains limited. This project focuses on chlorotoxin, a 36-amino-acid peptide derived from the scorpion Leiurus quinquestriatus, stabilized by four disulfide bonds. Chlorotoxin selectively binds to cancer-associated targets such as MMP-2, Annexin-2, and calcium-activated chloride ion channels, showing high specificity toward glioma cells. In this work, chlorotoxin was engineered for applications in photodynamic therapy, PROTAC development, and Gallium-68 chelation for radioisotopic imaging of gliomas. The second project addresses antimicrobial resistance (AMR), a major global health challenge driving the need for new therapeutics. This work focuses on thanatin, a 21-amino-acid β-hairpin antimicrobial peptide active against both Gram-positive and Gram-negative bacteria. To improve its proteolytic stability, selected residues were modified using non-canonical amino acids such as 2-aminoisobutyric acid (Aib) and a β-oxy-δ-threonine dipeptide mimetic. These modifications were designed to preserve the peptide’s β-hairpin structure and antimicrobial activity while enhancing stability, contributing to the development of next-generation antimicrobial therapeutics.