Mechanisms of recognition and binding of α-TTP to the plasma membrane by multi-scale molecular dynamics simulations

Lamprakis, Christos; Stocker, Achim; Cascella, Michele (2015). Mechanisms of recognition and binding of α-TTP to the plasma membrane by multi-scale molecular dynamics simulations. Frontiers in Molecular Biosciences, 2(36) Frontiers 10.3389/fmolb.2015.00036

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We used multiple sets of simulations both at the atomistic and coarse-grained level of resolution to investigate interaction and binding of α-tochoperol transfer protein (α-TTP) to phosphatidylinositol phosphate lipids (PIPs). Our calculations indicate that enrichment of membranes with such lipids facilitate membrane anchoring. Atomistic models suggest that PIP can be incorporated into the binding cavity of α-TTP and therefore confirm that such protein can work as lipid exchanger between the endosome and the plasma membrane. Comparison of the atomistic models of the α-TTP-PIPs complex with membrane-bound α-TTP revealed different roles for the various basic residues composing the basic patch that is key for the protein/ligand interaction. Such residues are of critical importance as several point mutations at their position lead to severe forms of ataxia with vitamin E deficiency (AVED) phenotypes. Specifically, R221 is main residue responsible for the stabilization of the complex. R68 and R192 exchange strong interactions in the protein or in the membrane complex only, suggesting that the two residues alternate contact formation, thus facilitating lipid flipping from the membrane into the protein cavity during the lipid exchange process. Finally, R59 shows weaker interactions with PIPs anyway with a clear preference for specific phosphorylation positions, hinting a role in early membrane selectivity for the protein. Altogether, our simulations reveal significant aspects at the atomistic scale of interactions of α-TTP with the plasma membrane and with PIP, providing clarifications on the mechanism of intracellular vitamin E trafficking and helping establishing the role of key residue for the functionality of α-TTP.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Lamprakis, Christos; Stocker, Achim and Cascella, Michele

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry

ISSN:

2296-889X

Publisher:

Frontiers

Language:

English

Submitter:

Achim Stocker

Date Deposited:

31 Aug 2015 17:50

Last Modified:

31 Aug 2015 17:50

Publisher DOI:

10.3389/fmolb.2015.00036

BORIS DOI:

10.7892/boris.71377

URI:

https://boris.unibe.ch/id/eprint/71377

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