Machado Mello De Sousa, T., Gorsche, R., Jovanović, B., Mach, R. L., & Mach-Aigner, A. R. (2022). In Vitro Characterization of a Nuclear Receptor-like Domain of the Xylanase Regulator 1 from Trichoderma reesei. Journal of Fungi, 8(12), Article 1254. https://doi.org/10.3390/jof8121254
Engineering transcription factors is an interesting research target gaining increasing attention, such as in the case of industrially used organisms. With respect to sustainability, biomass-degrading saprophytic fungi, such as Trichoderma reesei, are promising industrial work horses because they exhibit a high secretory capacity of native and heterologously expressed enzymes and compounds. A single-point mutation in the main transactivator of xylanase and cellulase expressions in T. reesei Xyr1 led to a strongly deregulated and enhanced xylanase expression. Circular dichroism spectroscopy revealed a change in secondary structure caused by this mutation. According to electrophoretic mobility shift assays and determination of the equilibrium-binding constants, the DNA-binding affinity of the mutated Xyr1 was considerably reduced compared to the wild-type Xyr1. Both techniques were also used to investigate the allosteric response to carbohydrates (D-glucose-6-phosphate, D-xylose, and sophorose) signalling the repression or induction of Xyr1 target genes. The mutated Xyr1 no longer exhibited a conformational change in response to these carbohydrates, indicating that the observed deregulation is not a simple matter of a change in DNA-binding of the transactivator. Altogether, we postulate that the part of Xyr1 where the mutation is located functions as a nuclear receptor-like domain that mediates carbohydrate signals and modulates the Xyr1 transactivating activity.
Ein pleiotroper Regulator des Sekundärmetabolismus Ein synthetisches Expressionssystem für das T. reesei Xyr1 Regulon
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