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Sub-nanometre mapping of the aquaporin-water interface with multifrequency atomic force microscopy

Ricci, M.; Quinlan, R.A.; Voïtchovsky, K.

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Authors

M. Ricci



Abstract

Aquaporins are integral membrane proteins that regulate the transport of water and small molecules in and out of the cell. In eye lens tissue, circulation of water, ions and metabolites is ensured by a microcirculation system in which aquaporin-0 (AQP0) plays a central role. AQP0 allows water to flow beyond the diffiusion limit through lens membranes where it naturally arranges in a square lattice. Malfunction of AQP0 is related to numerous deseases such as cataract. Despite considerable research into its structure, function and dyanmics, the interface between the protein and the surrounding liquid and the effect of the lattice arrangement on the behaviour of water at the interface with the membrane are still not fully understood. Here we use a multifrequency atomic force microscopy (AFM) approach to map both the liquid at the interface with AQP0 and the protein itself with sub-nanometer resolution. Imaging using the fundamental eigenmode of the AFM cantilever probes mainly the interfacial water at the surface of the membrane. Results highlight a well-defined region that surrounds AQP0 tetramers and where water exhibits a higher affinity for the protein. Imaging at the second eigenmode is dominated by the mechanical response of the protein and provides sub-molecular details of the protein surface and sub-surface structure. The relationship between modes and harmonics is also examined.

Citation

Ricci, M., Quinlan, R., & Voïtchovsky, K. (2017). Sub-nanometre mapping of the aquaporin-water interface with multifrequency atomic force microscopy. Soft Matter, 13(1), 187-195. https://doi.org/10.1039/c6sm00751a

Journal Article Type Article
Acceptance Date Jun 15, 2016
Online Publication Date Jun 16, 2016
Publication Date Jan 7, 2017
Deposit Date Jun 27, 2016
Publicly Available Date Jun 29, 2016
Journal Soft Matter
Print ISSN 1744-683X
Electronic ISSN 1744-6848
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 13
Issue 1
Pages 187-195
DOI https://doi.org/10.1039/c6sm00751a

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