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. Author manuscript; available in PMC: 2018 Aug 18.
Published in final edited form as: ACS Chem Biol. 2018 Jun 12;13(8):2161–2169. doi: 10.1021/acschembio.8b00336

Figure 5.

Figure 5

Application of one-color assay to membrane permeabilization by the antimicrobial peptide LL-37. Top: Red fluorescence and phase contrast snapshots of single zy3720 E. coli cell following addition of 4 μM LL-37 (1X MIC) plus 100 nM JF646 ligand at t = 0. Time resolution is 6 sec/cycle = 0.1 min/cycle. Bottom: Time dependence of cell length (from phase contrast images) and HaloTag-JF646 conjugate fluorescence intensity for the same cell. The fluorescence builds up in the periplasm for ~10 min, prior to the onset of significant cell shrinkage. Abrupt loss of some 75% of the intensity is attributed to OM permeabilization to globular proteins including GFP, HaloTag protein and HaloTag-JF646 conjugate. Simultaneous loss of GFP and HaloTag-JF646 conjugate was demonstrated in the two-color experiment of Figure S3. Scale bar is 1 μm.