Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 28, 2005
Publication Date: May 1, 2005
Citation: Savary, B.J., Nunez, A., Cameron, R.G. 2005. Identification of plant pectin methylesterase isoforms by mass spectromety peptide profiling. Meeting Abstract. Annual Meeting of American Society of Plant Biologists. Paper #999. Technical Abstract: Pectin methylesterases (PMEs, E.C. 220.127.116.11) are cell wall enzymes that catalyze hydrolysis of O6 methyl-esterified D-galactosiduronic acid units in pectin. They occur in multigene families and are commonly expressed in plant tissues. They vary in their biochemical optima, specificity, and action on pectin substrates. Such differences presumably reflect considerable diversity and complexity of function in cell wall metabolism. PME isoform-specific identities, determined by structural characterization, are frequently not documented in published reports due to the complexity and labor intensity in preparing monocomponent enzymes. We have isolated the multiple PME forms present in Valencia orange fruit to better understand their biochemical and structural properties and their action on pectin. In this presentation, we demonstrate application of new proteomic tools for matching peptide mass fingerprints generated from individual PMEs isolated from Valencia orange fruit tissue with theoretical peptide libraries generated from corresponding PME nucleic acid sequence data. The approach is highly accurate for detecting both conserved and isoform-specific peptide ion signatures, providing unequivocal identification between structurally similar PME isoforms. The approach described provides a general means for rapidly identifying PME isoforms present in plant tissues.