Chromatin Regulators Ahc1p and Eaf3p Positively Influence Nitrogen Metabolism in Saccharomyces cerevisiae

Chromatin Regulation of Acetic Acid Stress Tolerance by Ino80 in Budding Yeast Saccharomyces cerevisiae

Enhanced environmental stress tolerance is important for microbial production of biofuels and biobased chemicals. However, the roles of chromatin regulation in stress tolerance and bioproduction remain unclear. Here, we explore the effects of Ino80, the core subunit of the INO80 chromatin remodeling complex, on yeast stress adaptation. We found that deletion of INO80 led to increased sensitivity of budding yeast Saccharomyces cerevisiae to acetic acid, which is a common inhibitor in lignocellulosic biomass and also serves as a food preservative. Integrated ATAC-seq and RNA-seq analyses further showed that deleting INO80 resulted in extensive changes in chromatin accessibility and gene expression in cell wall-related genes. Genetic interaction between INO80 and AHC2, which is a subunit of the ADA acetyltransferase complex was proved, and the direct role of INO80 in the expression of AHC2 transcription was also confirmed. These findings benefit the development of robust yeast strains and food preservatives by targeting chromatin regulation.

Chromatin regulator Eaf3p regulates nitrogen metabolism in Saccharomyces cerevisiae as a trans-acting factor

IMPORTANCE

In this study, the mechanism of chromatin regulator Eaf3p regulating nitrogen metabolism in S. cerevisiae was investigated. It provides theoretical support for epigenetic modifications of cells to alter the level of histone modifications, coordinate the expression of multiple genes, and make it more conducive to the co-metabolism of multiple nitrogen sources. Moreover, it provides new ideas for industrial brewing yeast strains to achieve nitrogen source metabolism balance, reduce the accumulation of harmful nitrogen metabolites, and improve fermentation efficiency. This study provides a reference for changing the performance of microbial strains and improving the quality of traditional fermentation products and provides a theoretical basis for studying epigenetic modification and nitrogen metabolism regulation. It has an important theoretical explanation and practical application value. In addition, this study also provides useful clues for the study.

Identification of key genes through the constructed CRISPR-dcas9 to facilitate the efficient production of O-acetylhomoserine in Corynebacterium glutamicum

O-Acetylhomoserine (OAH) is an important platform chemical for the synthesis of L-methamidophos and l-methionine. It has been produced efficiently in Corynebacterium glutamicum. However, a wider range of key factors had not been identified, limiting further increases in OAH production. This study successfully identified some limiting factors and regulated them to improve OAH titer. Firstly, an efficient clustered regularly interspaced short palindromic repeats/dead CRISPR associated protein 9 (CRISPR-dCas9) system was constructed and used to identify the key genes in central metabolism and branch pathways associated with OAH biosynthesis. Then, the gltA gene involved in TCA cycle was identified as the most critical gene. A sequential promoter P_NCgl2698, which showed different transcriptional intensity in different strain growth periods, was used to control the expression of gltA gene, resulting in OAH production of 7.0 g/L at 48 h. Finally, the OAH titer of the engineered strain reached 25.9 g/L at 72 h in a 5-L bioreactor. These results show that the identification and regulation of key genes are critical for OAH biosynthesis, which would provide a better research basis for the industrial production of OAH in C. glutamicum.