Roles of pectin methylesterases (PMEs) in plant development : How to fine-tune the degree of methylesterification of pectins ?
The fine-tuning of the degree of methylesterification of cell wall pectin is a key to regulate cell elongation and ultimately the shape of plant body. Pectin methylesterification is spatio-temporally controlled by pectin methylesterases (PMEs, 66 members in Arabidopsis). The comparably large number of proteinaceous pectin methylesterase inhibitors (PMEIs) questions the specificity of the PME-PMEI interaction and the functional role of such abundance. We first characterized the role of PMEs in regulating cell expansion during dark-grown hypocotyl. In this simple model, developmental and cell biology, genomics, biochemistry, and biophysics can be integrated at a cellular level. Using mutant plants impaired for the expression of PME2 and PME32, we show how PMEs can mediate changes in pectin chemistry and cell wall mechanics, with consequent effects on elongation. To gain more insights into the fine tuning of PME activity, we characterized PME-PMEI interactions. For this purpose, we combined biochemistry and Molecular Dynamic (MD) simulations approaches to assess the determinants of the pH-dependence of the interaction. Using site-directed mutagenesis, we confirmed the role of specific amino acids in modulating the interaction. MD simulation have proven to be powerful to predict the differences between PMEI, allowing the discovery of a strategy that may be used by PMEIs to inhibit PMEs in different micro-environmental conditions and paving the way to identify the specific role of distinct PMEIs in muro.
Animated by :
Dr Jérôme PELLOUX
Laboratoire de Biologie des Plantes et Innovation (BioPI), Université de Picardie Jules Verne
Invited by the group « Fibres végétales »
on Friday 20th May 2016 at 10.30am at building C9 – room André Verbert