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Interfacial Choline-Aromatic Cation-Pi Interactions Can Contribute as Much to Peripheral Protein Affinity for Membranes as Aromatics Inserted Below the Phosphates

preprint
submitted on 04.06.2019 and posted on 05.06.2019 by Qaiser Waheed, Hanif M. Khan, Tao He, Mary Roberts, Anne Gershenson, Nathalie Reuter
Membrane binding interfaces of peripheral proteins are restricted to a small part of their exposed surface so the ability to engage in strong selective interactions with membrane lipids at various depths in the interface, both below and above the phosphates, is an advantage. Driven by their hydrophobicity aromatic amino acids preferentially partition into membrane interfaces often below the phosphates. Yet enthalpically favorable interactions with the lipid headgroups, above the phosphate plane, are likely to further stabilize high interfacial positions. Using Free Energy Perturbation we calculate the energetic cost of alanine substitution for 11 interfacial aromatic amino acids from 3 peripheral proteins. We show that involvement in cation-π interactions with the headgroups (i) increases the ΔΔGtransfer as compared to insertion at the same depth without cation-π stabilization and (ii) can contribute at least as much as deeper insertion below the phosphates, highlighting the multiple roles of aromatics in peripheral membrane protein affinity.

Funding

Norges Forskningsråd (#214167, #251247)

National Institute of General Medical Sciences (R01GM060418)

History

Email Address of Submitting Author

nathalie.reuter@uib.no

Institution

University of Bergen

Country

Norway

ORCID For Submitting Author

0000-0002-3649-7675

Declaration of Conflict of Interest

None

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