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The yeast Saccharomyces cerevisiae is a widely used platform for the production of heterologous proteins of either therapeutic or industrial interest. However, heterologous protein productivity is often low due to limitations of the selected host strain (1). In the case of the α-amylase, overproduction by S. cerevisiae may lead to an intracellular accumulation of reactive oxygen species (ROS) as a consequence of the formation of disulfide bonds during protein folding in the endoplasmic reticulum, and therefore causing a significant decrease in the cell performance which ultimately affects the protein titer and productivity (2). In order to reduce the internal ROS levels, we describe a strategy based on the overexpression of the Hap1 transcription factor, known to be responsible for both the activation of a set of genes involved in ROS detoxification and the oxidative stress response, as well as genes related to the respiratory metabolism (3). This strategy resulted to have a positive effect in the protein production by increasing the final titer compared to the control strains, while keeping the ROS levels constant during batch cultivations. 1. Hou J, Osterlund T, Liu Z, Petranovic D, Nielsen J. 2013. Heat shock response improves heterologous protein secretion in Saccharomyces cerevisiae. Appl Microbiol Biotechnol 97:3559-3568. 2. Liu Z, Osterlund T, Hou J, Petranovic D, Nielsen J. 2013. Anaerobic alpha- amylase production and secretion with fumarate as the final electron acceptor in Saccharomyces cerevisiae. Appl Environ Microbiol 79:2962- 2967. 3. Zhang L, Hach A. 1999. Molecular mechanism of heme signaling in yeast: the transcriptional activator Hap1 serves as the key mediator. Cell Mol Life Sci 56:415-426. |
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