Similarly with previous reported [11, 12], most genes involved in ergosterol biosynthesis were repressed for both strains in this study. It is possible that the regulatory functions of the biosynthesis may not be significantly affected at transcriptional levels under the conditions of this study. The PDR gene group is a new set of genes examined for ethanol tolerance in this study. Many PDR genes function as transporters of ATP-binding cassette proteins and are encoded for plasma membrane proteins that mediate membrane translocation of ions and a wide range of substrates. It impacts lipid and cell wall compositions and major facilitator

superfamily proteins for cell detoxifications [60]. We previously found that PDR genes and regulatory elements played significant roles for tolerance and in situ detoxification of lignocellulose-derived inhibitors [61]. Selleck AZD6244 Since plasma membrane and cell walls are major targets of ethanol damages, we anticipated the involvement of these genes for reconditioning and remodeling membrane

and cell walls in response to ethanol challenges. The significantly enriched background of transcriptional Selleckchem CB-839 abundance and continuously increased expressions of several genes in this group for the ethanol tolerant yeast observed in this study support our hypothesis (Table 3). The expressions of PDR genes are mainly controlled by transcription factor Pdr1p and Pdr3p [62]. As demonstrated in our study, many genes share the common transcription protein binding motif of Pdr1p/Pdr3p. Expressions of PDR1 in the tolerant Y-50316 Cyclin-dependent kinase 3 was not significantly induced but constantly expressed at all time

points compared with the parental strain. It needs to be pointed out that unless it is repressed, PDR1 does not have to be greatly induced to allow potential Pdr1p functions as a regulator [32, 60]. We consider the ability of its expression under the stress is a tolerance response and suggest Pdr1p as a potential regulator involving the ethanol tolerance of Y-50316. As discussed above, genes able to express or recover to express normally under the stress are SHP099 important to maintain gene interactions and cell functions. On the other hand, transcription factor genes MSN4, MSN2, YAP1 and HSF1 of the tolerant strains were highly abundance under the ethanol stress. Since many ethanol tolerance candidate genes sharing protein binding motifs of Msn4p/Msn2p, Yap1p and Hsf1p, these transcription factors are likely a core set of regulators for interactive expressions of ethanol tolerance. An HSF1-deletion mutant showed repressed expressions for its target genes usually induced by ethanol [63]. It has been demonstrated that Msn2p and Msn4p induces gene expression via a stress response element and triggers transcriptional response of the downstream genes [64, 65]. Condition-specific roles in gene expression regulation by these transcription factors were also suggested [66].