title: The Absence of the Transcription Factor Yrr1p, Identified from Comparative Genome Profiling, Increased Vanillin Tolerance Due to Enhancements of ABC Transporters Expressing, rRNA Processing and Ribosome Biogenesis inSaccharomyces cerevisiae.
abstract: Enhancing the tolerance ofSaccharomyces cerevisiaeto inhibitors derived from lignocellulose is conducive to producing biofuel and chemicals using abundant lignocellulosic materials. Vanillin is a major type of phenolic inhibitor in lignocellulose hydrolysates forS. cerevisiae. In the present work, the factors beneficial to vanillin resistance in yeast were identified from the vanillin-resistant strain EMV-8, which was derived from strain NAN-27 by adaptive evolution. We found 450 SNPs and 44 genes with InDels in the vanillin-tolerant strain EMV-8 by comparing the genome sequences of EMV-8 and NAN-27. To investigate the effects of InDels, InDels were deleted in BY4741, respectively. We demonstrated that the deletion ofYRR1improved vanillin tolerance of strain. In the presence of 6 mM vanillin, deletingYRR1increase the maximum specific growth rate and the vanillin consumption rate by 142 and 51%, respectively. The subsequent transcriptome analysis revealed that deletingYRR1resulted in changed expression of over 200 genes in the presence of 5 mM vanillin. The most marked changes were the significant up-regulation of the dehydrogenaseADH7, several ATP-binding cassette (ABC) transporters, and dozens of genes involved in ribosome biogenesis and rRNA processing. Coincidently, the crude enzyme solution of BY4741(yrr1Δ) exhibited higher NADPH-dependent vanillin reduction activity than control. In addition, overexpressing the ABC transporter genesPDR5, YOR1, andSNQ2, as well as the RNA helicase geneDBP2, increased the vanillin tolerance of strain. Interestingly, unlike the marked changes we mentioned above, under vanillin-free conditions, there are only limited transcriptional differences between wildtype andyrr1Δ. This indicated that vanillin might act as an effector in Yrr1p-related regulatory processes. The new findings of the relationship betweenYRR1and vanillin tolerance, as well as the contribution of rRNA processing and ribosome biogenesis to enhancingS. cerevisiaevanillin tolerance, provide novel targets for genetic engineering manipulation to improve microbes' tolerance to lignocellulose hydrolysate.
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China.
authors.forename: Xinning
authors.initials: X
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China.
authors.forename: Zhenzhen
authors.initials: Z
authors.lastname: Liang
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Hou
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Shen
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong UniversityJinan, China; Shandong Provincial Key Laboratory of Microbial Engineering, Department of Bioengineering, Qilu University of TechnologyJinan, China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Bao
keywords: ABC transporters; ADH7; YRR1; budding yeast; rRNA processing; ribosome synthesis; vanillin tolerance