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Identification of cellulose synthase AtCesA7 (IRX3) in vivo phosphorylation sites - a potential role in regulating protein degradation

Taylor, N.G. (2007) Identification of cellulose synthase AtCesA7 (IRX3) in vivo phosphorylation sites - a potential role in regulating protein degradation. Plant Molecular Biology, 64 (1-2). pp. 161-171. ISSN 0167-4412

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Cellulose is central to plant development and is synthesised at the plasma membrane by an organised protein complex that contains three different cellulose synthase proteins. The ordered assembly of these three catalytic subunits is essential for normal cellulose synthesis. The way in which the relative levels of these three proteins are regulated within the cell is currently unknown. In this work it is shown that one of the cellulose synthases essential for secondary cell wall cellulose synthesis in Arabidopsis thaliana, AtCesA7, is phosphorylated in vivo. Analysis of in vivo phosphorylation sites by mass spectrometry reveals that two serine residues are phosphorylated. These residues occur in a region of hyper-variability between the cellulose synthase catalytic subunits. The region of the protein containing these phosphorylation sites can be phosphorylated by a plant extract in vitro. Incubation of this region with plant extracts results in its degradation via a proteasome dependant pathway. Full length endogenous CesA7 is also degraded via a proteasome dependant pathway in whole plant extracts. This data suggests that phosphorylation of the catalytic subunits may target them for degradation via a proteasome dependant pathway. This is a possible mechanism by which plants regulate the relative levels of the three proteins whose specific interaction are required to form an active cellulose synthase complex.

Item Type: Article
Institution: The University of York
Academic Units: The University of York > Biology (York)
Depositing User: York RAE Import
Date Deposited: 25 Feb 2009 12:09
Last Modified: 25 Feb 2009 12:09
Published Version: http://dx.doi.org/10.1007/s11103-007-9142-2
Status: Published
Publisher: Springer Science + Business Media
Identification Number: 10.1007/s11103-007-9142-2
URI: http://eprints.whiterose.ac.uk/id/eprint/7224

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