Engineering Tocopherol Selectivity in alpha-TTP: A Combined In Vitro/In Silico Study

Helbling, Rachel E.; Aeschimann, Walter; Simona, Fabio; Stocker, Achim; Cascella, Michele (2012). Engineering Tocopherol Selectivity in alpha-TTP: A Combined In Vitro/In Silico Study. PLoS ONE, 7(11), e49195. Lawrence, Kans.: Public Library of Science 10.1371/journal.pone.0049195

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"We present a combined in vitro/in silico study to determine the molecular origin of the selectivity of a-tocopherol transfer" "protein (a-TTP) towards a-tocopherol. Molecular dynamics simulations combined to free energy perturbation calculations predict a binding free energy for a-tocopherol to a-TTP 8.26+2.13 kcal mol{1 lower than that of c-tocopherol. Our calculations show that c-tocopherol binds to a-TTP in a significantly distorted geometry as compared to that of the natural ligand. Variations in the hydration of the binding pocket and in the protein structure are found as well. We propose a mutation, A156L, which significantly modifies the selectivity properties of a-TTP towards the two tocopherols. In particular, our simulations predict that A156L binds preferentially to c-tocopherol, with striking structural similarities to the wild-type- a-tocopherol complex. The affinity properties are confirmed by differential scanning fluorimetry as well as in vitro competitive binding assays. Our data indicate that residue A156 is at a critical position for determination of the selectivity of a-TTP. The engineering of TTP mutants with modulating binding properties can have potential impact at industrial level for easier purification of single tocopherols from vitamin E mixtures coming from natural oils or synthetic processes. Moreover," "the identification of a c-tocopherol selective TTP offers the possibility to challenge the hypotheses for the evolutionary development of a mechanism for a-tocopherol selection in omnivorous animals."

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Aeschimann, Walter; Simona, Fabio; Stocker, Achim and Cascella, Michele

Subjects:

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

ISSN:

1932-6203

Publisher:

Public Library of Science

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 14:37

Last Modified:

13 Dec 2014 18:21

Publisher DOI:

10.1371/journal.pone.0049195

Web of Science ID:

000311234600028

BORIS DOI:

10.7892/boris.14786

URI:

https://boris.unibe.ch/id/eprint/14786 (FactScience: 221909)

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