Kinetics of antimicrobial peptide activity measured on individual bacterial cells using high-speed atomic force microscopy


Observations of real-time changes in living cells have contributed much to the field of cellular biology. The ability to image whole, living cells with nanometre resolution on a timescale that is relevant to dynamic cellular processes has so far been elusive1,2. Here, we investigate the kinetics of individual bacterial cell death using a novel high-speed atomic force microscope optimized for imaging live cells in real time. The increased time resolution (13 s per image) allows the characterization of the initial stages of the action of the antimicrobial peptide CM15 on individual Escherichia coli cells with nanometre resolution. Our results indicate that the killing process is a combination of a time-variable incubation phase (which takes seconds to minutes to complete) and a more rapid execution phase.

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Figure 1: Small AFM cantilevers for high-speed AFM.
Figure 2: Escherichia coli cell disruption induced by CM15, imaged with high-speed AFM.
Figure 3: AmP-induced surface morphology change correlates to cell death.
Figure 4: Early-stage kinetics of CM15 action measured by AFM correlates with bulk killing activity experiment.


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The authors would like to thank T. Chau for helpful discussions about antimicrobial peptides. G.E.F. is supported by an Erwin- Schrödinger fellowship J2778-B12. R.J.B. is the recipient of a National Institutes of Health Biotechnology Training Program Fellowship. A.M.B. would like to thank the Massachusetts Institute of Technology for their generous support. This work was further funded by the Army Research Office through the Institute for Soldier Nanotechnology, the National Institute of Health under Award RO1 GM065354 and by the Austrian Research Promotion Agency under award no. VO156-08-BII: NSI-FABICAN.

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G.E.F. and R.J.B. contributed to experimental design and execution and writing of the manuscript. D.S.G. designed the methods and sample preparation. A.M.B. contributed to experimental design, supervision and editing of the manuscript.

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Correspondence to Angela M. Belcher.

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Fantner, G., Barbero, R., Gray, D. et al. Kinetics of antimicrobial peptide activity measured on individual bacterial cells using high-speed atomic force microscopy. Nature Nanotech 5, 280–285 (2010).

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