title: Related alphaN- and epsilonN-methyltransferases methylate the large and small subunits of Rubisco.
abstract: Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is methylated at the ax amino position of the N-terminal methionyl residue of the processed and assembled form of the small subunit (SS), and is also methylated in some species at the epsilon-amino group of lysine-14 in the large subunit (LS). The gene (rbcMT-S) and cDNAs for the SS alphaN-methyltransferase (SSMT) from spinach (Spinach oleracea) have been cloned, sequenced, and expressed. The gene is closely related to a previously characterized LS methyltransferase (Rubisco LSMT) cDNA from pea (Rubisco LSMT) and a Rubisco LSMT gene from tobacco. Sequence analysis of the cDNA and transcript mapping experiments demonstrate that the rbcMT-S pre-mRNAs experience alternative 3' splice site selection, such that mRNAs for a long form with a four amino acid insertion and a short form are expressed at approximately equal abundance. The coding sequence of spinach SSMT includes a putative targeting presequence with sequence identity at a plastid processing site. A N-terminal truncated form of spinach SSMT was expressed and purified from E. coli cells. Both long and short forms of the cDNAs were shown to catalyze methylation of the a amine of the N-terminal methionine of the SS of Rubisco.
authors.affiliation: Department of Horticulture & Landscape Architecture, University of Kentucky, Lexington 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: M
authors.initials: M
authors.lastname: Royer
authors.forename: R L
authors.initials: RL
authors.lastname: Houtz
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001483:Base Sequence; D008745:Methylation; D008780:Methyltransferases / Q000378:metabolism*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D012273:Ribulose-Bisphosphate Carboxylase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D018724:Spinacia oleracea / Q000201:enzymology
chemical_list: D012333:RNA, Messenger; D008780:Methyltransferases; D012273:Ribulose-Bisphosphate Carboxylase