Molecular Genetics and Genomics

, Volume 275, Issue 2, pp 125–135

Substrate specificity of N-methyltransferase involved in purine alkaloids synthesis is dependent upon one amino acid residue of the enzyme


  • Naho Yoneyama
    • Graduate School of Humanities and SciencesOchanomizu University
  • Hanayo Morimoto
    • Graduate School of Humanities and SciencesOchanomizu University
  • Chuang-Xing Ye
    • School of Life SciencesSun Yat-Sen University
  • Hiroshi Ashihara
    • Department of Biology, Fuculty of ScienceOchanomizu University
  • Kouichi Mizuno
    • Faculty of Bioresource of ScienceAkita Prefectural University
    • Graduate School of Humanities and SciencesOchanomizu University
Original Paper

DOI: 10.1007/s00438-005-0070-z

Cite this article as:
Yoneyama, N., Morimoto, H., Ye, C. et al. Mol Genet Genomics (2006) 275: 125. doi:10.1007/s00438-005-0070-z


Caffeine (1,3,7-trimethylxanthine) and theobromine (3,7-dimethylxanthine) are the major purine alkaloids in plants. To investigate the diversity of N-methyltransferases involved in purine alkaloid biosynthesis, we isolated the genes homologous for caffeine synthase from theobromine-accumulating plants. The predicted amino acid sequences of N-methyltransferases in theobromine-accumulating species in Camellia were more than 80% identical to caffeine synthase in C. sinensis. However, there was a little homology among the N-methyltransferases between Camellia and Theobroma. The recombinant enzymes derived from theobromine-accumulating plants had only 3-N-methyltransferase activity. The accumulation of purine alkaloids was, therefore, dependent on the substrate specificity of N-methyltransferase determined by one amino acid residue in the central part of the protein.


CaffeineCaffeine synthaseCamellia, TheobromineTheobromine synthaseTheobroma cacao

Copyright information

© Springer-Verlag 2005