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. 2023 Mar 1;14:1170. doi: 10.1038/s41467-023-36280-y

Fig. 1. CpoBD13 is a histidine-rich β-defensin that permeabilises C. albicans in a pH-dependent manner.

Fig. 1

a Full-length peptide sequence of CpoBD13. Connecting lines represent disulphide bonds between cysteine residues. b Sequence alignment of CpoBD13 with its close homologues A. sinensis (Chinese alligator) β-defensin 13 (AsBD13, GenBank accession code AUG31287.1) and Gallus gallus (chicken) avian β-defensin 13 (AvBD13, NCBI RefSeq NP_001001780.1). c Fungal growth inhibition assay of C. albicans treated with CpoBD13 over a 24 h period. d Membrane permeabilisation of C. albicans after a 30 min treatment with CpoBD13 as determined by the uptake of propidium iodide. e MTT and MTS cell viability assay of human primary (AHDF and HUVEC) and tumourigenic (HeLa, PC3 and U937) cells treated with a range of CpoBD13 concentrations after 48 h. f Net charge of CpoBD13 at pH 5–9 highlights a sharp decrease in positive charge at pH greater than 6.0. The theoretical net charge of the peptide was calculated using a simplified method based on the pKa of free amino acids. g Membrane permeabilisation of C. albicans treated with CpoBD13 in conditions buffered to pH 5.5, 6.5 and 7.5. Data in (c–e & g) represent mean ± SEM, n = 3. h Live microscopy of C. albicans treated with 20 µM CpoBD13 conjugated to the fluorophore BODIPY FL EDA (green) in the presence of PI (orange). Images are representative of three independent experiments. i Live microscopy of the accumulation of CpoBD13-BODIPY (20 µM, green) at the plasma membrane of C. albicans cells. Scale bars represent 10 µm. Images are representative of three independent experiments. (c–g) Source data are provided as a Source Data file.