This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (22) Citing Articles via Google Scholar Google Scholar Articles by Houtz, R. L. Articles by Salvucci, M. E. Search for Related Content PubMed PubMed Citation Articles by Houtz, R. L. Articles by Salvucci, M. E. Agricola Articles by Houtz, R. L. Articles by Salvucci, M. E.

Metabolism and Enzymology

Partial Purification and Characterization of Ribulose-1,5-bisphosphate Carboxylase/Oxygenase Large Subunit N-Methyltransferase ¹

Department of Horticulture and Landscape Architecture, Plant Physiology/Biochemistry/Molecular Biology Program, University of Kentucky, Lexington, Kentucky 40546, United States Department of Agriculture-Agricultural Research Service, University of Kentucky, Lexington, Kentucky 40546

The large subunit (LS) of tobacco (Nicotiana rustica) ribulose-1,5-bisphosphate carboxylase/oxygenase (ribulose-P₂ carboxylase) contains a trimethyllysyl residue at position 14, whereas this position is unmodified in spinach ribulose-P₂ carboxylase. A protein fraction was isolated from tobacco chloroplasts by rate-zonal centrifugation and anion-exchange fast protein liquid chromatography that catalyzed transfer of methyl groups from S-adenosyl-[methyl-³H]-L-methionine to spinach ribulose-P₂ carboxylase. ³H-Methyl groups incorporated into spinach ribulose-P₂ carboxylase were alkaline stable but could be removed by limited tryptic proteolysis. Reverse-phase high-performance liquid chromatography of the tryptic peptides released after proteolysis showed that the penultimate N-terminal peptide from the LS of spinach ribulose-P₂ carboxylase contained the site of methylation, which was identified as lysine-14. Thus, the methyltransferase activity can be attributed to S-adenosylmethionine:ribulose-P₂ carboxylase LS (lysine) `N-methyltransferase, a previously undescribed chloroplast enzyme. The partially purified enzyme was specific for ribulose-P₂ carboxylase and exhibited apparent K_m values of 10 micromolar for S-adenosyl-L-methionine and 18 micromolar for ribulose-P₂ carboxylase, a V_max of 700 picomoles CH₃ groups transferred per minute per milligram protein, and a broad pH optimum from 8.5 to 10.0. S-Adenosylmethionine:ribulose-P₂ carboxylase LS (lysine)N-methyltransferase was capable of incorporating 24 ³H-methyl groups per spinach ribulose-P₂ carboxylase holoenzyme, forming 1 mole of trimethyllysine per mole of ribulose-P₂ carboxylase LS, but was inactive on ribulose-P₂ carboxylases that contain a trimethyllysyl residue at position 14 in the LS. The enzyme did not distinguish between activated (Mg²⁺ and CO₂) and unactivated forms of ribulose-P₂ carboxylase as substrates. However, complexes of activated ribulose-P₂ carboxylase with the reaction-intermediate analogue 2'-carboxy-D-arabinitol-1,5-bisphosphate, or unactivated spinach ribulose-P₂ carboxylase with ribulose-1,5-bisphosphate, were poor substrates for tobacco LS N-methyltransferase.

This article has been cited by other articles:

				R. L. Houtz, R. Magnani, N. R. Nayak, and L. M. A. Dirk Co- and post-translational modifications in Rubisco: unanswered questions J. Exp. Bot., May 1, 2008; 59(7): 1635 - 1645. [Abstract] [Full Text] [PDF]

				J.-F. Couture, G. Hauk, M. J. Thompson, G. M. Blackburn, and R. C. Trievel Catalytic Roles for Carbon-Oxygen Hydrogen Bonding in SET Domain Lysine Methyltransferases J. Biol. Chem., July 14, 2006; 281(28): 19280 - 19287. [Abstract] [Full Text] [PDF]

				B. Rathinasabapathi, W. M. Fouad, and C. A. Sigua {beta}-Alanine Betaine Synthesis in the Plumbaginaceae. Purification and Characterization of a Trifunctional, S-Adenosyl-L-Methionine-Dependent N-Methyltransferase from Limonium latifolium Leaves Plant Physiology, July 1, 2001; 126(3): 1241 - 1249. [Abstract] [Full Text] [PDF]

				Z. Ying, R. M. Mulligan, N. Janney, and R. L. Houtz Rubisco Small and Large Subunit N-Methyltransferases. BI- AND MONO-FUNCTIONAL METHYLTRANSFERASES THAT METHYLATE THE SMALL AND LARGE SUBUNITS OF RUBISCO J. Biol. Chem., December 17, 1999; 274(51): 36750 - 36756. [Abstract] [Full Text] [PDF]