Research Institute of Innovative Technology for the Earth, Kizugawa, Japan.
Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan.
FEBS J. 2024 Oct;291(20):4489-4500. doi: 10.1111/febs.17240. Epub 2024 Aug 7.
Ideonella sakaiensis is a bacterium that can degrade and consume polyethylene terephthalate (PET), a plastic material that was previously considered non-biodegradable. The degradation of PET requires two enzymes, namely poly (ethylene terephthalate) hydrolase (PETase) and mono (2-hydroxyethyl) terephthalate hydrolase (MHETase), which break down PET into terephthalate (TPA) and ethylene glycol (EG), which serve as carbon sources for the bacterium. Previous studies have focused on the enzymatic properties, structure, and mechanism of action of PETase and MHETase. However, the regulation of PETase and MHETase gene expression has not been investigated. This study identified a protein that binds to the MHETase promoter DNA, MHETase gene-regulating protein (MRP) in I. sakaiensis. PET or TPA induced the expression of PETase and MHETase genes. Furthermore, the induction of the MHETase gene was abolished by the deletion of the mrp gene, while the expression of the PETase gene was maintained. In addition, the genes involved in TPA metabolism were not induced in the mrp mutant. Furthermore, the growth of the PET and TPA deteriorated due to mrp mutation. Also, MRP binds to the promoter regions of the MHETase gene and TPA metabolizing genes, but not to the PETase gene promoter. These results suggest that MRP is a transcription factor that activates MHETase and TPA-metabolizing genes.
解朊假丝酵母是一种能够降解和消耗聚对苯二甲酸乙二醇酯（PET）的细菌，而 PET 是一种此前被认为不可生物降解的塑料材料。PET 的降解需要两种酶，即聚对苯二甲酸乙二醇酯水解酶（PETase）和单（2-羟乙基）对苯二甲酸水解酶（MHETase），它们将 PET 分解为对苯二甲酸（TPA）和乙二醇（EG），这些物质可作为细菌的碳源。先前的研究主要集中在 PETase 和 MHETase 的酶学特性、结构和作用机制上。然而，对于 PETase 和 MHETase 基因表达的调控机制尚未进行研究。本研究在解朊假丝酵母中鉴定出一种与 MHETase 启动子 DNA 结合的蛋白质，即 MHETase 基因调控蛋白（MRP）。PET 或 TPA 诱导 PETase 和 MHETase 基因的表达。此外，mrp 基因缺失会使 MHETase 基因的诱导作用丧失，而 PETase 基因的表达则得以维持。此外，mrp 突变体中不诱导 TPA 代谢相关基因的表达。此外，由于 mrp 突变，PET 和 TPA 的生长受到了影响。此外，MRP 与 MHETase 基因和 TPA 代谢基因的启动子区域结合，但不与 PETase 基因启动子结合。这些结果表明，MRP 是一种转录因子，可激活 MHETase 和 TPA 代谢基因。
