William Plaxton - Professor

Research: Our research focuses on the organization and control of plant carbohydrate metabolism, the biochemical adaptations of phosphate-starved plants, and enzyme control by phosphorylation, monoubiquitination, and glycosylation. This work employs classical and modern biochemical, proteomic, and genetic tools to characterize the molecular and functional properties of key enzyme proteins. Systems that we are currently studying include developing and germinating castor oilseeds, and suspension cell cultures and seedlings of the model plant Arabidopsis thaliana. Our results are integrated with a wide range of information on genomics, the control of gene expression, protein structure-function, metabolomics, and whole plant physiology into a framework that leads to a deeper understanding of how plants work in their natural environment. These studies also have significant applications to problems in the ag-biotech industry including the: (1) targeted modification of storage oil versus protein levels in oilseeds such as canola or soybean, and  (2) development of phosphate-efficient crops, urgently needed to reduce mankind’s rampant but inefficient use of non-renewable, unsustainable, and polluting phosphate fertilizers.

»» Lab Website »« email: plaxton@queensu.ca »« telephone: 613-533-6150 ««

Some Recent Publications (students indicated by asterisks):

• O'Leary* B, Rao S, Plaxton WC (2011) Phosphorylation of a bacterial-type phosphoenolpyruvate carboxylase at serine-425 provides a further tier of enzyme control in developing castor oil seeds. Biochemical Journal 433: 65-74
• Tran* HT, Qian W, Hurley* BA, She Y-M, Wang D, Plaxton WC (2010) Biochemical and molecular characterization of AtPAP12 and AtPAP26: the predominant purple acid phosphatases isozymes secreted by phosphate-starved Arabidopsis thaliana. Plant, Cell & Environment  33: 1789-1803
• Hurley* BA, Tran* HT, Murty N, Park J, Snedden WA, Mullen RT, Plaxton WC (2010) The dual-targeted purple acid phosphatase isozyme AtPAP26 is essential for efficient acclimation of Arabidopsis thaliana to nutritional phosphate deprivation. Plant Physiology 153:1112–1122
• Tran* HT, Hurley* BA, Plaxton WC (2010) Feeding hungry plants: The role of purple acid phosphatases in phosphate nutrition. Plant Science 179: 14-27
• O'Leary* B, Rao S, Kim* J, Plaxton WC (2009) Bacterial-type phosphoenolpyruvate carboxylase (PEPC) functions as a catalytic and regulatory subunit of the novel class-2 PEPC complex of vascular plants. Journal of Biological Chemistry 284: 24797-243805
• Gregory* AL, Hurley* BA, Tran* HT, Valentine AJ, She Y-M, Knowles VL, Plaxton WC (2009) In vivo regulatory phosphorylation of the phosphoenolpyruvate carboxylase AtPPC1 in phosphate-starved Arabidopsis thaliana. Biochemical Journal 420: 57-65
• Uhrig* RG, She Y-M, Leach CA, Plaxton WC (2008) Regulatory monoubiquitination of phosphoenolpyruvate carboxylase in germinating castor oil seeds. Journal of Biological Chemistry 283: 29650-29657  (selected by the Editors as a JBC ‘paper of the week’)
• Tran* HT, Plaxton WC (2008) Proteomic analysis of alterations in the secretome of Arabidopsis thaliana suspension cells subjected to nutritional phosphate deficiency. Proteomics 8: 4317-4326
• Uhrig* RG, O’Leary* B, Spang* HE, MacDonald JA, She Y-M, Plaxton WC (2008) Co-immunopurification of phosphorylated bacterial- and plant-type phosphoenolpyruvate carboxylases with the plastidial pyruvate dehydrogenase complex from developing castor oil seeds. Plant Physiology 146: 1346-1357