Format

Send to

Choose Destination
J Biol Chem. 2015 Sep 18;290(38):23320-35. doi: 10.1074/jbc.M115.639534. Epub 2015 Jul 16.

Tuning of Pectin Methylesterification: PECTIN METHYLESTERASE INHIBITOR 7 MODULATES THE PROCESSIVE ACTIVITY OF CO-EXPRESSED PECTIN METHYLESTERASE 3 IN A pH-DEPENDENT MANNER.

Author information

1
From the EA3900-BIOPI, Biologie des Plantes et Innovation and.
2
INRA, UMR 1268, Biopolymères-Interactions-Assemblages, BP 71627, 44316 Nantes, France.
3
the Laboratoire de Glycobiologie et Matrice Extracellulaire Végétale, UPRES EA 4358, Institut de Recherche et d'Innovation Biomédicale, Grand Réseau de Recherche-Végétal, Agronomie, Sol, Innovation, UFR des Sciences et Techniques, Normandie Université-Université de Rouen, 76821 Mont-Saint-Aignan Cedex 1, France.
4
the Departments of Computer Sciences and.
5
Plateforme d'Ingénierie Cellulaire and Analyses des Protéines (ICAP), Université de Picardie Jules Verne, 80039 Amiens, France.
6
Biological Sciences, Purdue University, West Lafayette, Indiana 47907.
7
the Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg, Denmark, and.
8
the LRSV, UMR 5546 Université Toulouse 3/CNRS, 31326 Castanet-Tolosan, France.
9
the Departments of Computer Sciences and Biological Sciences, Purdue University, West Lafayette, Indiana 47907.
10
From the EA3900-BIOPI, Biologie des Plantes et Innovation and catherine.rayon@u-picardie.fr.

Abstract

Pectin methylesterases (PMEs) catalyze the demethylesterification of homogalacturonan domains of pectin in plant cell walls and are regulated by endogenous pectin methylesterase inhibitors (PMEIs). In Arabidopsis dark-grown hypocotyls, one PME (AtPME3) and one PMEI (AtPMEI7) were identified as potential interacting proteins. Using RT-quantitative PCR analysis and gene promoter::GUS fusions, we first showed that AtPME3 and AtPMEI7 genes had overlapping patterns of expression in etiolated hypocotyls. The two proteins were identified in hypocotyl cell wall extracts by proteomics. To investigate the potential interaction between AtPME3 and AtPMEI7, both proteins were expressed in a heterologous system and purified by affinity chromatography. The activity of recombinant AtPME3 was characterized on homogalacturonans (HGs) with distinct degrees/patterns of methylesterification. AtPME3 showed the highest activity at pH 7.5 on HG substrates with a degree of methylesterification between 60 and 80% and a random distribution of methyl esters. On the best HG substrate, AtPME3 generates long non-methylesterified stretches and leaves short highly methylesterified zones, indicating that it acts as a processive enzyme. The recombinant AtPMEI7 and AtPME3 interaction reduces the level of demethylesterification of the HG substrate but does not inhibit the processivity of the enzyme. These data suggest that the AtPME3·AtPMEI7 complex is not covalently linked and could, depending on the pH, be alternately formed and dissociated. Docking analysis indicated that the inhibition of AtPME3 could occur via the interaction of AtPMEI7 with a PME ligand-binding cleft structure. All of these data indicate that AtPME3 and AtPMEI7 could be partners involved in the fine tuning of HG methylesterification during plant development.

KEYWORDS:

degree of blockiness; gel diffusion assay; homology modeling; microscale thermophoresis; pectin methylesterase (PME); pectin methylesterase inhibitor (PMEI); plant biochemistry; plant cell wall; protein expression; protein-protein interaction

PMID:
26183897
PMCID:
PMC4645611
DOI:
10.1074/jbc.M115.639534
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center