Kinetic manifestation of processivity during multiple methylations catalyzed by SET domain protein methyltransferases

Lynnette M.A. Dirk, E. Megan Flynn, Kevin Dietzel, Jean François Couture, Raymond C. Trievel, Robert L. Houtz

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


Processive versus distributive methyl group transfer was assessed for pea Rubisco large subunit methyltransferase, a SET domain protein lysine methyltransferase catalyzing the formation of trimethyllysine-14 in the large subunit of Rubisco. Catalytically competent complexes between an immobilized form of des(methyl) Rubisco and Rubisco large subunit methyltransferase were used to demonstrate enzyme release that was co-incident with and dependent on formation of trimethyllysine. Catalytic rate constants determined for formation of trimethyllysine were considerably lower (∼10-fold) than rate constants determined for total radiolabel incorporation from [3H-methyl]-S- adenosylmethionine. Double-reciprocal velocity plots under catalytic conditions favoring monomethyllysine indicated a random or ordered reaction mechanism, while conditions favoring trimethyllysine suggested a hybrid ping-pong mechanism. These results were compared with double-reciprocal velocity plots and product analyses obtained for HsSET7/9 (a monomethyltransferase) and SpCLR4 (a dimethyltransferase) and suggest a predictive ability of double-reciprocal velocity plots for single versus multiple methyl group transfers by SET domain protein lysine methyltransferases. A model is proposed for SET domain protein lysine methyltransferases in which initial binding of polypeptide substrate and S-adenosylmethionine is random, with polypeptide binding followed by deprotonation of the ε-amine of the target lysyl residue and subsequent methylation. Following methyl group transfer, S-adenosylhomocysteine and monomethylated polypeptide dissociate from monomethyltransferases, but di- and trimethyltransferases begin a successive and catalytically obligatory deprotonation of enzyme-bound methylated lysyl intermediates, which along with binding and release of S-adenosylmethionine and S-adenosylhomocysteine is manifested as a hybrid ping-pong-like reaction mechanism.

Original languageEnglish
Pages (from-to)3905-3915
Number of pages11
Issue number12
StatePublished - Mar 27 2007

ASJC Scopus subject areas

  • Biochemistry


Dive into the research topics of 'Kinetic manifestation of processivity during multiple methylations catalyzed by SET domain protein methyltransferases'. Together they form a unique fingerprint.

Cite this