Metabolism of homocysteine-thiolactone in plants

Hieronim Jakubowski, Andrzej Guranowski

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Editing of the amino acid homocysteine (Hcy) by certain aminoacyl-tRNA synthetases results in the formation of an intramolecular thioester, Hcy-thiolactone. Here we show that the plant yellow lupin, Lupinus luteus, has the ability to synthesize Hcy-thiolactone. The inhibition of methylation of Hcy to methionine by the anitifolate drug aminopterin results in greatly enhanced synthesis of Hcy-thiolactone by L. luteus plants. Methionine inhibits the synthesis of Hcy-thiolactone in L. luteus, suggesting involvement of methionyl-tRNA synthetase. Consistent with this suggestion is our finding that the plant Oryza sativa methionyl-tRNA synthetase, expressed in Escherichia coli, catalyzes conversion of Hcy to Hcy-thiolactone. We also show that Hcy is a component of L. luteus proteins, most likely due to facile reaction of Hcy-thiolactone with protein amino groups. In addition, L. luteus possesses constitutively expressed, highly specific Hcy-thiolactone-hydrolyzing enzyme. Thus, Hcy-thiolactone and Hcy bound to protein by an amide (or peptide) linkage (Hcy-N-protein) are significant components of plant Hcy metabolism.

Original languageEnglish (US)
Pages (from-to)6765-6770
Number of pages6
JournalJournal of Biological Chemistry
Volume278
Issue number9
DOIs
StatePublished - Feb 28 2003

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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