Skip to Main content Skip to Navigation
Theses

Caractérisation biochimique et structurale de quelques glutathion transférases de la classe Tau d'arabette (Arabidopsis thaliana) et de peuplier (Populus trichocarpa)

Abstract : Glutathione transferases (GSTs) constitute a ubiquitous multigene superfamily of enzymes involved in xenobiotic detoxification and secondary metabolism. Canonical GSTs consist of an N-terminal thioredoxin domain and a α-helical C-terminal domain. In terrestrial plants, GSTs can be grouped in 14 classes but also according to the conserved residue found in their catalytic site either cysteine (Cys-GSTs) or serine (Ser-GSTs) GSTs. Ser-GSTs exhibit reduction of peroxides and/or glutathione (GSH) conjugation activities while Cys-GSTs rather exhibit deglutathionylation and dehydroascorbate reductase activities. Some of them also appear to have non-catalytic ligandin properties for the transport or storage of various molecules. The plant-specific Tau GST (GSTU) class is usually the most expanded one. The GSTUs are often over-expressed during biotic and abiotic stresses contributing notably to herbicide detoxification. However, the physiological role of most GSTUs is still poorly documented in planta. By combining phylogenetic, biochemical and structural approaches, this work led to the characterisation of nine GSTUs from Arabidopsis thaliana (AtGSTUs) and six GSTUs from Populus trichocarpa (PtGSTUs). Phylogenetic analysis of the Ser-GSTs present in photosynthetic organisms revealed that the expansion of GSTUs occurred concomitantly with the appearance of vasculature in plants, although some mosses and bryophytes possess GSTUs. Within an organism, GSTUs can be classified into distinct groups according to their catalytic motif. Enzymatic tests using recombinant proteins showed that almost all studied GSTUs exhibit GSH conjugation and peroxide reduction activities against different model substrates (CDNB, isothiocyanate derivatives, hydroperoxides). The three-dimensional structures of two GSTUs have been resolved and these adopt the classical canonical GST fold with some notable difference between them. The biochemical and structural analyses of these AtGSTUs and PtGSTUs further showed that some of them bind bacterial porphyrins while others bind polyphenolic compounds. Among the enzyme-ligand complexes identified, the structure of a bacalein-GSTU has been solved. The use of metabolites enriched samples extracted from A. thaliana and P. trichocarpa is the next step to decipher the role of GSTUs in planta.
Document type :
Theses
File URL :
https://docnum.univ-lorraine.fr/ulprive/DDOC_T_2020_0253_SYLVESTRE_GONON.pdf
Complete list of metadata

https://hal.univ-lorraine.fr/tel-03284796
Contributor : Thèses Ul <>
Submitted on : Monday, July 12, 2021 - 7:42:02 PM
Last modification on : Tuesday, July 13, 2021 - 3:55:07 AM

Identifiers

  • HAL Id : tel-03284796, version 1

Collections

Citation

Elodie Sylvestre-Gonon. Caractérisation biochimique et structurale de quelques glutathion transférases de la classe Tau d'arabette (Arabidopsis thaliana) et de peuplier (Populus trichocarpa). Biochimie, Biologie Moléculaire. Université de Lorraine, 2020. Français. ⟨NNT : 2020LORR0253⟩. ⟨tel-03284796⟩

Share

Metrics

Record views

15