EMIHP (2017-2018)

Molecular Study of Herbicide-Protein D1 Interactions in Tetraselmis suecica

Ifremer Coordination	Type of project	Financing	Project duration	Link
R. Sussarellu (LEX)	National	Ifremer DS (Politique de Site)	2017-2018

The EMIHP project aims to study the interactions between two antifouling herbicides (diuron and irgarol) and their target, photosystem II (PSII), on two strains of the microalgae Tetraselmis suecica: a wild strain and a strain resistant to diuron. The interactions were studied for the two molecules in mixture and alone to characterize their effects on T. suecica, at the molecular level with the D1 protein of the PSII with three-dimensional models were developed. The objective of this multidisciplinary project is to help rationalize the mixing effects of the two herbicides. This project took place in collaboration with the ModES (Modeling and Spectroscopy) team of the CEISAM laboratory (University of Nantes), specialized in the study of the structure, properties and/or non-covalent interactions of molecular systems.

Ifremer staff	Academic partners
S. Stachowski-Haberkorn (LEX)	Laboratoire CEISAM (Univ Nantes)

Principle results :

In addition to the precise determination of the toxicity threshold values (EC₅₀) of the two substances on the two strains, the project has shown that, although not resistant to irgarol, the mutant strain is half as sensitive to this substance than the wild strain. Additionally, a slight but significant synergy between diuron and irgarol was confirmed in the mutant strain. A transcriptomic analysis by RNAseq made possible to obtain the reference transcriptome for T. suecica and highlight the metabolic pathways differentially expressed between the control conditions and those exposed to a diuron/irgarol mixture for the two strains.

Molecular Modeling work has led to the identification of the interactions between each herbicide (diuron, irgarol) and the 3D models of the D1/D2 proteins developed for wild-type and mutated strains. Unexpectedly, the identified mutation has no significant effect on the mode of herbicide attachment. The sequential methodological approach adopted made possible to explore the influence of several parameters and to acquire additional data.

Publications :

Sussarellu R., Dupraz V., Menard D., Budzinski H., Stachowski-Haberkorn S. Responses of two strains of the marine microalga Tetraselmis suecica to binary mixtures of two PSII inhibitors. Colloque International Ecotoxicomic, Lyon, Novembre 2017.

Bouchouireb Z., Stachowski-Haberkon S., Sussarellu R., Graton J., Le Questel JY. Binding mode of diuron and irgarol with PSII reaction core of wild and diuron-resistant strains of a microalgae: insights from molecular docking. Congrès international RICT (Interfacing Chemical Biology and Drug Discovery), Strasbourg, 4-6 Juillet 2018.