Ferredoxin:NAD + Oxidoreductase of Thermoanaerobacterium saccharolyticum and Its Role in Ethanol Formation
| Autor: | Lee R. Lynd, Tianyong Zheng, Jonathan Lo, Liang Tian, Xiongjun Shao, Daniel G. Olson |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
Applied Microbiology and Biotechnology Metabolic engineering 03 medical and health sciences Bacterial Proteins Oxidoreductase Ethanol metabolism Ferredoxin chemistry.chemical_classification Ethanol Ecology Gene Expression Regulation Bacterial NAD Metabolic pathway 030104 developmental biology chemistry Biochemistry Fermentation Ferredoxins Heterologous expression NAD+ kinase Oxidoreductases Oxidation-Reduction Thermoanaerobacterium Food Science Biotechnology |
| Zdroj: | Applied and Environmental Microbiology. 82:7134-7141 |
| ISSN: | 1098-5336 0099-2240 |
| DOI: | 10.1128/aem.02130-16 |
| Popis: | Ferredoxin:NAD + oxidoreductase (NADH-FNOR) catalyzes the transfer of electrons from reduced ferredoxin to NAD + . This enzyme has been hypothesized to be the main enzyme responsible for ferredoxin oxidization in the NADH-based ethanol pathway in Thermoanaerobacterium saccharolyticum ; however, the corresponding gene has not yet been identified. Here, we identified the Tsac_1705 protein as a candidate FNOR based on the homology of its functional domains. We then confirmed its activity in vitro with a ferredoxin-based FNOR assay. To determine its role in metabolism, the tsac_1705 gene was deleted in different strains of T. saccharolyticum . In wild-type T. saccharolyticum , deletion of tsac_1705 resulted in a 75% loss of NADH-FNOR activity, which indicated that Tsac_1705 is the main NADH-FNOR in T. saccharolyticum . When both NADH- and NADPH-linked FNOR genes were deleted, the ethanol titer decreased and the ratio of ethanol to acetate approached unity, indicative of the absence of FNOR activity. Finally, we tested the effect of heterologous expression of Tsac_1705 in Clostridium thermocellum and found improvements in both the titer and the yield of ethanol. IMPORTANCE Redox balance plays a crucial role in many metabolic engineering strategies. Ferredoxins are widely used as electron carriers for anaerobic microorganism and plants. This study identified the gene responsible for electron transfer from ferredoxin to NAD + , a key reaction in the ethanol production pathway of this organism and many other metabolic pathways. Identification of this gene is an important step in transferring the ethanol production ability of this organism to other organisms. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|