Comparative structural and functional analysis of phi class glutathione transferases involved in multiple-herbicide resistance of grass weeds and crops

: Georgakis N, Poudel N, Papageorgiou AC, Labrou NE

: 2020/02/24 0

: 2020

: Plant Physiology and Biochemistry

: 149

: 266

: 276

: 0981-9428

: 1873-2690

DOI: https://doi.org/10.1016/j.plaphy.2020.02.012

Multiple-herbicide resistant (MHR) weeds are a global problem and a looming threat to weed control in crops. MHR weeds express a specific phi classglutathione transferase (MHR-GSTF) which seems to contribute to herbicideresistance. The present work aims to investigate the structure and catalyticproperties of the MHR-GSTFs from different grass weeds and crops (Alopecurusmyosuroides, Lolium rigidum, Hordeum vulgare, Triticum aestivum). RecombinantMHR-GSTFs were expressed in E. coli and purified by affinity chromatography.Kinetic analysis of substrate specificity using a range of thiol substrates andxenobiotic compounds suggested that all enzymes display a broad range ofspecificity and are capable of detoxifying major stress-induced toxic products.Notably, all tested enzymes exhibited high activity towards organichydroperoxides. The crystal structure of MHR-GSTF from Alopecurus myosuroides(AmGSTF) was determined by molecular replacement at 1.33 A resolution. The enzymewas resolved with bound glutathione sulfenic acid (GSOH) at the G-site andsuccinic acid at the H-site. The enzyme shows conserved structural featurescompared to other Phi class GSTs. However, some differences were observed at theC-terminal helix H9 that may affect substrate specificity. The structural andfunctional features of AmGSTF were compared with those of the homologue cropenzymes (HvGSTF and TaGSTF) and discussed in light of their contribution to theMHR mechanism.CI - Copyright (c) 2020 Elsevier Masson SAS. All rights reserved.