# The non-catalytic binding of auxin, cytokinin and salicylic acid by tomato Phi class glutathione transferases: insights from computational modelling

## TL;DR

This study uses computational methods to show that a tomato enzyme, SlGSTF5, can bind plant hormones like auxin, suggesting new roles for these enzymes in plant biology.

## Contribution

The study identifies SlGSTF5 as a potential phytohormone binder and introduces a new computational protocol for analyzing such interactions.

## Key findings

- SlGSTF5 shows significant potential for non-catalytic binding of auxin and other phytohormones.
- A computational protocol was developed to model and analyze protein-ligand interactions in plant GSTs.

## Abstract

Glutathione transferases (GSTs, EC 2.5.1.18) are a diverse enzyme family involved in various cellular processes, regulated by several stimuli, including plant hormones (phytohormones). Additionally, GSTs can also influence hormone levels, as certain GSTs, particularly members of the Phi class GSTs (GSTFs) have been reported to directly bind small phytohormones (auxin, cytokinin, and salicylic acid). However, the structural aspects of these interactions remained unresolved. It has been documented that an Arabidopsis thaliana GSTF, AtGSTF2, possesses unique non-catalytic ligand-binding sites (L sites). This study focuses on the orthologous tomato (Solanum lycopersicum) GSTFs (SlGSTFs) and explores the connection between this non-catalytic ligand-binding function and phytohormones. Using modern in silico techniques, such as protein modelling by AlphaFold, molecular docking, and molecular dynamics (MD) simulations, we provide the first insights into the possible phytohormone-binding ability of SlGSTFs. In particular, SlGSTF5 shows significant potential for a novel phytohormone binding function, thereby broadening the potential roles of plant GSTs. Our work also includes a simple protocol for modelling and analysing protein-ligand interactions, offering valuable insights into the role of individual plant GSTs.

The online version contains supplementary material available at 10.1007/s11103-026-01681-2.

This study predicts tomato GSTs’ direct phytohormone binding, precisely SlGSTF5 with auxin, and presents a simple protocol using protein modeling and molecular dynamics simulations.

The online version contains supplementary material available at 10.1007/s11103-026-01681-2.