S cerevisiaeL-carnitine, a medically relevant, amino acid-derived molecule is a valuable target for biotechnological production. Researchers at the Institute for Wine Biotechnology, Stellenbosch University has recently provided the first report of a metabolically engineered carnitine producing strain of the industrial yeast, Saccharomyces cerevisiae, an organism that does not natively produce its own carnitine. This was achieved by cloning and reconstructing the Neurospora crassa L-carnitine biosynthesis pathway in the baker’s yeast to create an L-carnitine producing strain. The engineered yeast strains are able to catalyze the synthesis of L-carnitine from the pathway’s precursor, trimethyllysine, as well as from intermediates. Several native S. cerevisiae genes were identified that contribute to, or interfere with, the heterologous pathway. This includes (i) the threonine aldolase Gly1p which effectively catalyzed the second step of the pathway, fulfilling the role of a serine hydroxymethyltransferase, (ii) the arginine transporter Can1p which was identified as the yeast transporter for trimethyllysine, and (iii) the two serine hydroxymethyltransferases, Shm1p and Shm2p, which reduced the flux through the heterologous pathway. The work opens opportunities for using an engineered, L-carnitine producing S. cerevisiae strain in various industrial applications.

Published in Research Highlights