Chen Y, Pioli D, Piper P W
Department of Biochemistry and Molecular Biology, University College London, U.K.
Biotechnology (N Y). 1994 Aug;12(8):819-23. doi: 10.1038/nbt0894-819.
We have found an influence of cellular ubiquitin levels over the secretion of human leucocyte elastase inhibitor (elafin) by Saccharomyces cerevisiae. Inactivation of the UBI4 polyubiquitin gene reduced elafin secretion 3 to 4-fold. Conversely ubiquitin overexpression, by galactose induction of an integrated UBI4 gene under GAL1 promoter control, enhanced elafin secretion 7-fold compared to cells wild-type for ubiquitin genes. This influence of ubiquitin levels is exerted at a post-transcriptional step in elafin gene expression, and may represent a chaperone-like action. Ubiquitin overexpression did not affect production of alpha-factor and of certain natural yeast extracellular enzymes even though appreciable free ubiquitin became associated with the yeast periplasm.
