title: Rubisco small and large subunit N-methyltransferases. Bi- and mono-functional methyltransferases that methylate the small and large subunits of Rubisco.
abstract: Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco)is methylated at the alpha-amino group of the N-terminal methionine of the processed form of the small subunit (SS), and at the epsilon-amino group of lysine-14 of the large subunit (LS) in some species. The Rubisco LS methyltransferase (LSMT) gene has been cloned and expressed from pea and specifically methylates lysine-14 of the LS of Rubisco. We determine here that both pea and tobacco Rubisco LSMT also exhibit (alpha)N-methyltransferase activity toward the SS of Rubisco, suggesting that a single gene product can produce a bifunctional protein methyltransferase capable of catalyzing both (alpha)N-methylation of the SS and (epsilon)N-methylation of the LS. A homologue of the Rubisco LSMT gene (rbcMT-S) has also been identified in spinach that is closely related to Rubisco LSMT sequences from pea and tobacco. Two mRNAs are produced from rbcMT-S, and both long and short forms of the spinach cDNAs were expressed in Escherichia coli cells and shown to catalyze methylation of the alpha-amino group of the N-terminal methionine of the SS of Rubisco. Thus, the absence of lysine-14 methylation in species like spinach is apparently a consequence of a monofunctional protein methyltransferase incapable of methylating Lys-14, with activity limited to methylation of the SS.
authors.affiliation: Plant Physiology/Biochemistry/Molecular Biology Program, Department of Horticulture, University of Kentucky, Lexington, Kentucky 40546-0091, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Ying
authors.forename: R M
authors.initials: RM
authors.lastname: Mulligan
authors.forename: N
authors.initials: N
authors.lastname: Janney
authors.forename: R L
authors.initials: RL
authors.lastname: Houtz
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D011495:Histone-Lysine N-Methyltransferase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008745:Methylation; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism*; D012273:Ribulose-Bisphosphate Carboxylase / Q000737:chemistry* / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D018076:DNA, Complementary; D010940:Plant Proteins; C097344:ribulose-1,5-bisphosphate carboxylase-oxygenase large subunit epsilonN-methyltransferase; D011495:Histone-Lysine N-Methyltransferase; D012273:Ribulose-Bisphosphate Carboxylase