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Ann Bot. 2014 Oct;114(6):1161-75. doi: 10.1093/aob/mcu035. Epub 2014 Mar 24.

Arabidopsis PECTIN METHYLESTERASE17 is co-expressed with and processed by SBT3.5, a subtilisin-like serine protease.

Author information

1
EA3900-BIOPI Biologie des Plantes et Innovation, Université de Picardie, 33 Rue St Leu, F-80039 Amiens, France.
2
Universität Hohenheim, Institut für Physiologie und Biotechnologie der Pflanzen (260), D-70593 Stuttgart, Germany.
3
EA4358-Glyco-MEV, IFRMP 23, Université de Rouen, F-76821 Mont-Saint-Aignan, France.
4
ICAP, UPJV, 1-3 Rue des Louvels, F-80037 Amiens, France.
5
IJPB, UMR1318 INRA-AgroParisTech, Bâtiment 2, INRA Centre de Versailles-Grignon, Route de St Cyr (RD 10), F-78026 Versailles, France.
6
EA3900-BIOPI Biologie des Plantes et Innovation, Université de Picardie, 33 Rue St Leu, F-80039 Amiens, France jerome.pelloux@u-picardie.fr.

Abstract

BACKGROUND AND AIMS:

In Arabidopsis thaliana, the degree of methylesterification (DM) of homogalacturonans (HGs), the main pectic constituent of the cell wall, can be modified by pectin methylesterases (PMEs). In all organisms, two types of protein structure have been reported for PMEs: group 1 and group 2. In group 2 PMEs, the active part (PME domain, Pfam01095) is preceded by an N-terminal extension (PRO part), which shows similarities to PME inhibitors (PMEI domain, Pfam04043). This PRO part mediates retention of unprocessed group 2 PMEs in the Golgi apparatus, thus regulating PME activity through a post-translational mechanism. This study investigated the roles of a subtilisin-type serine protease (SBT) in the processing of a PME isoform.

METHODS:

Using a combination of functional genomics, biochemistry and proteomic approaches, the role of a specific SBT in the processing of a group 2 PME was assessed together with its consequences for plant development.

KEY RESULTS:

A group 2 PME, AtPME17 (At2g45220), was identified, which was highly co-expressed, both spatially and temporally, with AtSBT3.5 (At1g32940), a subtilisin-type serine protease (subtilase, SBT), during root development. PME activity was modified in roots of knockout mutants for both proteins with consequent effects on root growth. This suggested a role for SBT3.5 in the processing of PME17 in planta. Using transient expression in Nicotiana benthamiana, it was indeed shown that SBT3.5 can process PME17 at a specific single processing motif, releasing a mature isoform in the apoplasm.

CONCLUSIONS:

By revealing the potential role of SBT3.5 in the processing of PME17, this study brings new evidence of the complexity of the regulation of PMEs in plants, and highlights the need for identifying specific PME-SBT pairs.

KEYWORDS:

Arabidopsis thaliana; PME; SBT; co-expression; gene expression; pectin; pectin methylesterase; plant cell walls; post-translational modification; protein processing; subtilase; subtilisin-like serine protease

PMID:
24665109
PMCID:
PMC4195543
DOI:
10.1093/aob/mcu035
[Indexed for MEDLINE]
Free PMC Article

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