Protein Modification and Turnover
Magnani, Roberta , Dirk, Lynnette M.A. , Mazarei, Mitra , Houtz, Robert L. .
Regulation of chloroplast fructose- 1,6 bisphosphate aldolase activity due to methylation of Lys-391 by Rubisco PsLSMT.
Rubisco PsLSMT (EC. 18.104.22.168) catalyzes the trimethylation of lysine 14 on the large subunit of Rubisco. Rubisco PsLSMT is a highly conserved SET domain protein lysine methyltransferase (PKMT) found in all eukaryotic species. PKMTs have been known for exquisite polypeptide substrate specificity, but recent studies have clearly identified alternate substrates for some members of the PKMT family. In this study, tobacco plants with reduced expression of Rubisco PsLSMT were used to identify possible alternate substrate for Rubisco PsLSMT. In vitro labeling studies with [3H-methyl]AdoMet and mass spectrometry identified chloroplast fructose 1,6 bisphosphate aldolase (EC. 22.214.171.124; ALD) as one of several alternative substrates for PsLSMT. Rubisco PsLSMT catalyzed trimethylation of Lys-391 in the C-terminal tail region of ALD in vitro and the presence of a trimethyllysyl residue at this same position in vivo in ALD from untransformed tobacco plants was confirmed. The function of the methylation was investigated on purified ALD from transgenic and control plants, and preliminary studies revealed an increase of approximately three-fold in the aldolase cleavage activity compared with non-methylated ALD from Rubisco PsLSMT knock-down plants.
The source funding is DOE
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1 - University of Kentucky, Department of Horticulture, Plant Physiol./Biochem/Mol. Biol. Prog., 441 Plant Science Building, 1045 Veterans Drive, Lexington, KY, 40546-0312
2 - University of Kentucky, Department of Horticulture, Plant Physiol./Biochem/Mol. Biol. Prog.
3 - Iowa State University, Department of Plant Pathology
Rubisco Large Subunit Methyl Transferase
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM