Rebnegger Corinna, Graf Alexandra B, Valli Minoska, Steiger Matthias G, Gasser Brigitte, Maurer Michael, Mattanovich Diethard
Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria.
Biotechnol J. 2014 Apr;9(4):511-25. doi: 10.1002/biot.201300334. Epub 2014 Jan 14.
Protein production in yeasts is related to the specific growth rate μ. To elucidate on this correlation, we studied the transcriptome of Pichia pastoris at different specific growth rates by cultivating a strain secreting human serum albumin at μ = 0.015 to 0.15 h(-1) in glucose-limited chemostats. Genome-wide regulation revealed that translation-related as well as mitochondrial genes were upregulated with increasing μ, while autophagy and other proteolytic processes, carbon source-responsive genes and other targets of the TOR pathway as well as many transcriptional regulators were downregulated at higher μ. Mating and sporulation genes were most active at intermediate μ of 0.05 and 0.075 h(-1) . At very slow growth (μ = 0.015 h(-1) ) gene regulation differs significantly, affecting many transporters and glucose sensing. Analysis of a subset of genes related to protein folding and secretion reveals that unfolded protein response targets such as translocation, endoplasmic reticulum genes, and cytosolic chaperones are upregulated with increasing growth rate while proteolytic degradation of secretory proteins is downregulated. We conclude that a high μ positively affects specific protein secretion rates by acting on multiple cellular processes.
酵母中的蛋白质生产与比生长速率μ相关。为了阐明这种相关性，我们通过在葡萄糖限制的恒化器中培养一株分泌人血清白蛋白的菌株，使其比生长速率μ在0.015至0.15 h⁻¹之间，研究了不同比生长速率下毕赤酵母的转录组。全基因组调控显示，随着μ的增加，与翻译相关的基因以及线粒体基因上调，而自噬和其他蛋白水解过程、碳源响应基因以及TOR途径的其他靶点以及许多转录调节因子在较高的μ时下调。交配和孢子形成基因在0.05和0.075 h⁻¹的中等μ时最为活跃。在非常缓慢的生长（μ = 0.015 h⁻¹）时，基因调控有显著差异，影响许多转运蛋白和葡萄糖感应。对与蛋白质折叠和分泌相关的一组基因的分析表明，随着生长速率的增加，未折叠蛋白反应靶点如转运、内质网基因和胞质伴侣蛋白上调，而分泌蛋白的蛋白水解降解下调。我们得出结论，高μ通过作用于多个细胞过程对特定蛋白质分泌速率产生积极影响。
