ABSTRACT
The efficient fermentation of xylose can improve biofuel production. We previously developed a two-stage transcriptional reprogramming (TSTR) strategy (including a glucose fermentation stage and a xylose fermentation stage) and demonstrated its application for the construction of Saccharomyces cerevisiae strains with efficient xylose utilization. In this study, we used these as initial strains to assess the effects of copy number variation (CNV) on optimal gene expression and rewiring the redox balance of the xylose utilization pathway. We obtained strains that contained several integrated copies of XYL1, XYL2, and XKS1 and showed increased ethanol yields. An examination of the individual and combined effects of CNVs of key genes and the redox balance pathway revealed that the TSTR strategy improves ethanol production efficiency. Furthermore, XYL1 or XYL2 overexpression was related to improved xylose utilization. These results showed that strains with faster growth and/or higher ethanol production produced more ethanol from xylose via the synthetic xylose-assimilation pathway. Accordingly, TSTR is an effective strategy to improve xylose metabolism in industrial yeast strains.
Subject(s)
Carbohydrate Metabolism/genetics , Gene Expression Regulation, Fungal , Industrial Microbiology/methods , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , DNA Copy Number Variations , Ethanol/metabolism , Fermentation , Xylose/metabolismABSTRACT
The nuclear factor I (NFI) family members, especially NFIA and NFIB, play essential roles in cancers. The roles of NFIA and NFIB in esophageal squamous cell carcinoma (ESCC) and esophagogastric junction adenocarcinoma (EJA) remain poorly known. This study aimed to determine the expression of NFIA and NFIB in ESCC and EJA and elucidate their prognostic significance. The expression of NFIA and NFIB was examined in 163 ESCC samples and 26 EJA samples by immunohistochemistry. The results showed that high NFIA expression correlated significantly with poor differentiation, lymph node metastasis, and advanced TNM stage in patients with ESCC. High NFIB expression only correlated with poor differentiation in patients with ESCC. Survival analysis showed that NFIA but not NFIB associated with short overall survival (OS) and disease-free survival (DFS) of patients with ESCC. On the other hand, high NFIB expression correlated with lymph node metastasis, advanced TNM stage, and short OS and DFS in patients with EJA. Finally, multivariate analysis demonstrated that high NFIA expression was an independent prognostic factor for ESCC. Taken together, these results demonstrated that NFIA and NFIB could serve as prognostic indicators for ESCC and EJA, respectively.
