RNA-seq reveals the role of thiD in the thermal adaptation of Thermoanaerobacter tengcongensis

Abstract:

ThiD encoded by thiD in Thermoanaerobacter tengcongensis is a key enzyme in the biosynthesis of thiamine. The structure and functions of thiD have been elucidated in fungi, yeasts, and plants, while the role of thiD in thermophiles remains unclear. [Objective] This study aims to explore the thermal adaptation mechanism of T. tengcongensis and reveal the role of thiD in the thermal adaptation of T. tengcongensis at different temperatures. [Methods] The thiD-deleted mutant (ΔthiD) of T. tengcongensis was constructed by homologous recombination. The growth trends of the wild type (WT) and ΔthiD at 50 ℃, 60 ℃, 75 ℃, and 80 ℃ were observed and compared. The differentially expressed genes (DEGs) between ΔthiD and WT cultured at 75 ℃ were determined by RNA-seq. The transcript levels of 13 genes and 3 sRNAs in WT and ΔthiD at 50 ℃, 60 ℃, 75 ℃, and 80 ℃ were compared and analyzed by real-time PCR. [Results] ΔthiD was successfully constructed, with the growth rate not significantly different from WT at 50 ℃. However, ΔthiD show cased slower growth than WT at 60 ℃ and 75 ℃ and did not grow at 80 ℃. The transcriptome results revealed 503 DEGs in ΔthiD compared with WT, including 278 DEGs with up regulated expression and 213 DEGs with down regulated expression. The Kyoto encyclopedia of genes and genomes (KEGG) analysis indicated the following pathways associated with thermophilic adaptation, involving thiamine metabolism, pyrimidine metabolism and purine metabolism, peptidoglycan biosynthesis, fatty acid metabolism, amino acid metabolism, two-component system, DNA replication, homologous recombination, mismatch repair, and phosphotransferase system. The transcript levels of 13 genes and 3 sRNAs related to thermal adaptation in WT and ΔthiD changed at specific temperatures. [Conclusion] thiD plays an important role in the thermal adaptation of T. tengcongensis. This study provides experimental data and a theoretical basis for revealing the role of thiD in the thermal adaptation of thermophiles at different temperatures.