Enhanced Production of Cellobiohydrolase in the Recombinant Saccharomyces cerevisiae by MRP8 Overexpression

doi:10.13560/j.cnki.biotech.bull.1985.2018-0380

Abstract

Abstract: Cellulase production and secretion using budding yeast Saccharomyces cerevisiae as a host is one of the strategies for the production of cellulosic ethanol by consolidated bioprocessing（CBP）. However,the ability of cellulase secretion by S. cerevisiae still needs to be improved. Therefore,the aim of this study is to improve cellulase production by the recombinant yeast. It was reported that elevation of genes involved in oxidative stress tolerance improved cellulase production,we thus investigate the effect of overexpression of MRP8,which encodes the mitochondrial ribosomal protein in the recombinant yeast producing CBH1. MRP8 was overexpressed through CRISPR/Cas9 genome editing in the recombinant S. cerevisiae strain producing CBH1. The underlying mechanisms for improved CBH1 production were explored. Results showed that omparing with the control strain,the CBH1 activity was improved by 80% in the MRP8 overexpression strain,and no significant effect on growth ability was observed by MRP8 overexpression. Real-time quantitative PCR analysis showed that the transcription level of CBH1 was increased in the recombinant strain overexpressing MRP8,whereas,the transcription levels of key genes related to protein folding and secretion exhibited no change. No difference on cell growth in the presence of Congo red,Tunicamycin（TM）or Dithiothreitol（DTT）was observed. In addition,no significant difference in ATP content and reactive oxygen species（ROS）accumulation was detected. These results indicate that overexpression of MRP8 enhanced production of CBH1.

Key words: Saccharomyces cerevisiae, heterologous protein expression, cellobiohydrolase 1（CBH1）, mitochondrial ribosomal protein encoding gene MRP8, protein synthesis

WAN Qing-qing, LI Jie, ZENG Yu, ZHANG Ming-ming, ZHAO Xin-qing, BAI Feng-wu. Enhanced Production of Cellobiohydrolase in the Recombinant Saccharomyces cerevisiae by MRP8 Overexpression[J]. Biotechnology Bulletin, 2018, 34(5): 94-100.

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