Nanoconfined water in a channel-like protein

DIPC Seminars

Sara Capponi. Cardiovascular Research Institute, University of California in San Francisco, San Francisco, USA
Donostia International Physics Center. Pº Manuel Lardizabal 4, Donostia - San Sebastián
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Nanoconfined water in a channel-like protein Biomolecules are characterized by a very complex topography, which affects the organization of water molecules located close to their surface. Here I present a study on water confined in the SecY membrane protein, which constitutes the core of the SecYEG translocon complex. SecY is a membrane pore that mediates the insertion of proteins into cellular membranes. The insertion process has been explained experimentally in terms of the hydrophobic effect: the partitioning of a hydrophobic protein segment between the water-filled SecY interior and the membrane would resemble that between bulk water and membrane. theless, these partitioning processes exhibit strong differences, which might be due to the state of water inside SecY. By means of full-atom molecular dynamics simulations, I show that water motion is highly restricted within the SecY channel and water dipoles are aligned to the pore axis [1]. This might have implications for the SecY biological functions. Moreover, water confined into the SecY pore shares similarities with supercooled bulk water. [1] S. Capponi _et al._ , Proc. Natl. Acad. Sci. USA, 112 (29), 9016-9021 (2015).