Protein expression analysis revealed a fine-tuned mechanism of in situ detoxification pathway for the tolerant industrial yeast Saccharomyces cerevisiae

Authors: Liu, Zonglin; HUANG, XIAOQIU - Iowa State University; ZHOU, QIAN - Chinese Academy Of Sciences; XU, JIAN - Chinese Academy Of Sciences

Submitted to: Applied Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2019
Publication Date: 5/29/2019
Citation: Liu, Z., Huang, X., Zhou, Q., Xu, J. 2019. Protein expression analysis revealed a fine-tuned mechanism of in situ detoxification pathway for the tolerant industrial yeast Saccharomyces cerevisiae. Applied Microbiology and Biotechnology. 103:5781–5796. https://doi.org/10.1007/s00253-019-09906-9.
DOI: https://doi.org/10.1007/s00253-019-09906-9

Interpretive Summary: Overcoming the toxic compounds associated with lignocellulose-to-biofuel conversion possesses significant challenges to new strain development for a sustainable bio-based economy. Tolerant industrial yeast strains obtained by adaptation to lignocellulosic hydrolysates are able to detoxify a major class of inhibitory chemicals derived from lignocellulose-biomass pretreatment. Studies on the yeast tolerance have been carried out extensively; however, limited proteomic evidence is available on the mechanisms associated with its tolerance to the inhibitory chemicals. Using comparative time-course studies, with or without the toxic challenges to the yeast, this research revealed a key protein in central metabolism that is required for enhanced tolerance of the adapted strain. Critical roles for ribosomal proteins were also identified for the yeast adaptation to the toxic chemicals. Understanding the outcomes of the fine-tuned detoxification pathway facilitate development of the next-generation biocatalyst for sustainable production of fuels and chemicals from lignocellulosic materials. The new insight into the ribosomal protein involvement for yeast adaptation obtained from this study impacts the research and development communities in both basic and applied scientific investigations.

Technical Abstract: A tolerant industrial yeast Saccharomyces cerevisiae strain NRRL Y-50049 obtained through adaptive laboratory evolution is able to detoxify a major class of toxic aldehyde compounds in situ while producing ethanol. Here we describe Zwf1 as the key protein to drive glucose metabolism in favor of oxidative pentose phosphate pathway facilitating in situ detoxification of Y-50049 in comparative time-course studies. In the altered central metabolic pathway, Zwf1 enabled reduction of furfural and HMF through a group of aldehyde reduction enzymes by generating the essential cofactor NADPH. In return, the activated aldehyde reductions released desirable feedback of NADP+ for the oxidative reaction needed by Zwf1, thus restoring a well-maintained cofactor regeneration balance in response to the toxic challenge. In addition to this local change of the yeast adaptation, we identified signature expressions of 43 ribosomal proteins in Y-50049, including 35 essential ribosomal proteins, compared with its parental strain Y-12632 in response to synergistic challenges of furfural and HMF. The distinctive ribosome protein profiles and the increased frequency of sequence mutations in ribosomal protein genes RPL23A and RPS9B and ribosomal interactive ORF YNL208W in Y-50049 suggested critical involvement of ribosomal proteins in the yeast adaptation that reflect a potential ingrained alteration in the population of Y-50049 cells.