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Article Dans Une Revue The Plant cell Année : 2023

Plant polygalacturonase structures specify enzyme dynamics and processivities to fine-tune cell wall pectins

Wafae Tabi
Vanessa Ung
Olivier Habrylo
Aline Voxeur
Paula Pongrac
Solène Bassard
Serge Pilard
Davide Mercadante

Résumé

Polygalacturonases (PGs) fine-tune pectins to modulate cell wall chemistry and mechanics, impacting plant development. The large number of PGs encoded in plant genomes leads to questions on the diversity and specificity of distinct isozymes. Herein, we report the crystal structures of two Arabidopsis thaliana polygalacturonases, POLYGALACTURONASE LATERAL ROOT (PGLR) and ARABIDOPSIS DEHISCENCE ZONE POLYGALACTURONASE2 (ADPG2), which are co-expressed during root development. We first determined the amino acid variations and steric clashes that explain the absence of inhibition of the plant PGs by endogenous PG-Inhibiting Proteins (PGIPs). Although their beta helix folds are highly similar, PGLR and ADPG2 subsites in the substrate-binding groove are occupied by divergent amino acids. By combining molecular dynamic simulations, analysis of enzyme kinetics and hydrolysis products, we showed that these structural differences translated into distinct enzyme-substrate dynamics and enzyme processivities: ADPG2 showed greater substrate fluctuations with hydrolysis products, oligogalacturonides (OGs), with a degree of polymerization (DP) of ≤4, while the DP of OGs generated by PGLR was between 5 and 9. Using the Arabidopsis root as a developmental model, exogenous application of purified enzymes showed that the highly processive ADPG2 had major effects on both root cell elongation and cell adhesion. This work highlights the importance of PG processivity on pectin degradation regulating plant development.
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Dates et versions

hal-04106623 , version 1 (02-11-2023)

Identifiants

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Josip Safran, Wafae Tabi, Vanessa Ung, Adrien Lemaire, Olivier Habrylo, et al.. Plant polygalacturonase structures specify enzyme dynamics and processivities to fine-tune cell wall pectins. The Plant cell, 2023, pp.1-19. ⟨10.1093/plcell/koad134⟩. ⟨hal-04106623⟩
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