Abstract.
Cystathionine β-lyase (CbL) catalyses the second step in higher-plant methionine biosynthesis. To further characterise the role of CbL in methionine biosynthesis, transgenic potato (Solanum tuberosum L.) plants were generated that express a potato cystathionine β-lyase (StCbL; EC 4.4.1.8) under the control of the cauliflower mosaic virus 35 S promoter. Transgenic potato lines showed no visible phenotype but revealed an accumulation of both CbL transcript and protein. The enzymatic activity of CbL in these lines was up to 2.5-fold higher than that of wild-type plants. GC-MS measurements of aspartate-derived metabolites, however, showed no significant changes in content of amino acids and pathway intermediates when transgenic and wild-type plants were compared. CbL over-expression did not change the expression patterns and gene products of other pathway-relevant genes as evident from RNA and protein blot analyses. Despite the essential role of CbL in plant growth and development, the data presented indicate that the homologous over-expression of CbL is not in itself able to enhance metabolic flux towards methionine biosynthesis.
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Maimann, S., Hoefgen, R. & Hesse, H. Enhanced cystathionine β-lyase activity in transgenic potato plants does not force metabolite flow towards methionine. Planta 214, 163–170 (2001). https://doi.org/10.1007/s004250100651
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DOI: https://doi.org/10.1007/s004250100651