Signature gene expressions of cell wall integrity pathway concur with tolerance response of industrial yeast Saccharomyces cerevisiae against biomass pretreatment inhibitors

Authors: Liu, Zonglin

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/17/2015
Publication Date: 3/17/2015
Citation: Liu, Z.L. 2015. Signature gene expressions of cell wall integrity pathway concur with tolerance response of industrial yeast Saccharomyces cerevisiae against biomass pretreatment inhibitors [abstract]. Meeting Abstract. pp. 211-212..

Interpretive Summary:

Technical Abstract: Traditional industrial ethanologenic yeast Saccharomyces cerevisiae has a robust performance under various environmental conditions and can be served as a candidate for the next-generation biocatalyst development for advanced biofuels production using lignocellulose mateials. Overcoming toxic compounds liberated from lignocellulosic biomass pretreatment is among numerous challenges for a sustainable biofuels industry. In a genomic expression study for an industrial type strain NRRL Y-12632, key genes involved in cell wall integration signaling pathway, including WSC2, WSC3, FKS1, FSK2, PLC1, PKC1, BCK1, MKK1, MLP1, MLP2, RLM1, SWI4, and SWI6, were found to display distinct enhanced signature expressions in response to 30 mM 5-hydroxymethyl-2-furaldehyde (HMF), a commonly encountered biomass pretreatment inhibitory compound. Within 2h after HMF treatment, expressions of these genes increased to 3- to 4-fold higher comparing with an untreated control. Examination of most genes using analogous single-gene deletion mutations showed that all of these knock out mutants grew normally on a synthetic medium but failed to grow on the medium containing 20 mM HMF. These results suggest an essential role for each of these genes against HMF challenges. Since this tolerance response is adaptive, the cell wall integrity signaling pathway is likely involved in mediation to the tolerance of the industrial yeast against pretreatment inhibitors, in addition to other major regulatory elements. Sequence comparison of these genes from the industrial strain Y-12632 also revealed at least 42 non-synonymous SNPs, resulting in amino acid sequence substitutions, comparing with the reference model strain S288C using PCR sequencing analysis. The industrial yeast strain constantly shows more tolerance and adaptive responses to a wide range of inhibitory compounds than the model strain S288C. Variations in genomic sequence for the industrial yeast including concentrated SNPs involved in the cell wall integrity signaling pathway could attribute to this tolerance response.