Discovery and Characterization of a Disulfide-Locked C[subscript 2]-Symmetric Defensin Peptide

Abstract

We report the discovery of HD5-CD, an unprecedented C[subscript 2]-symmetric β-barrel-like covalent dimer of the cysteine-rich host-defense peptide human defensin 5 (HD5). Dimerization results from intermonomer disulfide exchange between the canonical α-defensin Cys[superscript II]–Cys[superscript IV] (Cys[superscript 5]–Cys[superscript 20]) bonds located at the hydrophobic interface. This disulfide-locked dimeric assembly provides a new element of structural diversity for cysteine-rich peptides as well as increased protease resistance, broad-spectrum antimicrobial activity, and enhanced potency against the opportunistic human pathogen Acinetobacter baumannii.