Vaccine makers and other pharmaceutical manufacturers using yeast protein-expression systems are taking note of a discovery this week by a team of researchers who have found RNA interference in Saccharomyces castellii. S. castellii is closely related to S. cerevisiae, a known eukaryotic model organism whose use in the pharmaceutical production has been cited (1).

“For a long time, people thought that budding yeast didn’t have RNAi at all because S. cerevisiae, which is the model budding yeast, doesn’t have RNAi,” said Kathleen Xie an undergraduate researcher in the laboratory of David Bartel, a professor at the Department of Biology at Massachusetts Institute of Technology (MIT; USA), in a press release issued by Whitehead Institute for Biomedical Research (USA). Xie and Bartel, also affiliated with the Howard Hughes Medical Institute, are two of the coauthors of the study published in the 10 September edition of Science Express. Other authors include I. Drinnenberg (Whitehead and Howard Hughes Medical Institute), D. Weinberg (Whitehead, Howard Hughes Medical and MIT), G. Fink (Whitehead and MIT), and J. Mower and K. Wolfe (both at Smurfit Institute of Genetics, Trinity College, Ireland).

The researchers hope that the discovery will lead to a greater understanding of the RNAi pathway, which is used by plants and animals to silence genes of viruses and transposons. Scientists also hope the finding will lead to more information about other yeasts, such as Candida albicans, a common human pathogen. Yeast expression systems offer several advantages in pharmaceutical production: their genomes are easy to manipulate, they grow quickly under controlled environments, and they have functions and biochemical pathways that are in common with human cells.

Reference
1. B. Huang et al., “Heterologous Production of Secondary Metabolites as Pharmaceuticals in Saccharomyces cerevisiae,” Biotechnol. Lett. 30 (7), 1121¬-1137 (2008).