Widespread utilization of polyethylene terephthalate (PET) has caused critical environmental pollution. The enzymatic degradation of PET is a promising solution to this problem. In this study, PETase, which exhibits much higher PET-hydrolytic activity than other enzymes, was successfully secreted into extracellular milieu from Bacillus subtilis 168 under the direction of its native signal peptide (named SP_PETase). SP_PETase is predicted to be a twin-arginine signal peptide. Intriguingly, inactivation of twin-arginine translocation (Tat) complexes improved the secretion amount by 3.8-fold, indicating that PETase was exported via Tat-independent pathway. To the best of our knowledge, this is the first report on the improvement of Tat-independent secretion by inactivating Tat components of B. subtilis 168 in LB medium. Furthermore, PET film degradation assay showed that the secreted PETase was fully active. This study paves the first step to construct an efficient engineered strain for PET degradation.

中文翻译：

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枯草芽孢杆菌168天然信号肽介导的聚对苯二甲酸乙二醇酯水解酶PETase的Tat非依赖性分泌

聚对苯二甲酸乙二酯（PET）的广泛使用已造成严重的环境污染。PET的酶促降解是解决该问题的有前途的解决方案。在这项研究中，表现出比其他酶更高的PET水解活性的PETase已成功地从枯草芽孢杆菌168分泌到其_自然信号肽（称为SP _PETase）的指导下，分泌到细胞外环境中。SP _PETase预计是双精氨酸信号肽。有趣的是，双精氨酸易位（Tat）复合物的失活使分泌量提高了3.8倍，表明PETase通过非Tat途径输出。据我们所知，这是关于通过灭活LB培养基中枯草芽孢杆菌168的Tat成分来改善Tat非依赖性分泌的首次报道。此外，PET膜降解试验表明分泌的PETase具有完全活性。这项研究为构建有效的PET降解工程菌株铺平了第一步。