The xylose oxidative pathway (XOP) is continuously gaining prominence as an alternative for the traditional pentose assimilative pathways in prokaryotes. It begins with the oxidation of D-xylose to D-xylonic acid, which is further converted to α-ketoglutarate or pyruvate + glycolaldehyde through a series of enzyme reactions. The persistent drawback of XOP is the accumulation of D-xylonic acid intermediate that causes culture media acidification. This study addresses this issue through the development of a novel pH-responsive synthetic genetic controller that uses a modified transmembrane transcription factor called CadCΔ. This genetic circuit was tested for its ability to detect extracellular pH and to control the buildup of D-xylonic acid in the culture media. Results showed that the pH-responsive genetic sensor confers dynamic regulation of D-xylonic acid accumulation, which adjusts with the perturbation of culture media pH. This is the first report demonstrating the use of a pH-responsive transmembrane transcription factor as a transducer in a synthetic genetic circuit that was designed for XOP. This may serve as a benchmark for the development of other genetic controllers for similar pathways that involve acidic intermediates.

中文翻译：

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一种pH响应型遗传传感器，用于动态调节大肠杆菌中D-木糖醛酸的积累。

作为原核生物中传统戊糖同化途径的替代品，木糖氧化途径（XOP）不断得到重视。它从D-木糖氧化为D-木糖酸开始，然后通过一系列酶反应将其进一步转化为α-酮戊二酸或丙酮酸+乙醇醛。XOP的持续缺点是D-木糖酸中间体的积累，导致培养基酸化。这项研究通过开发一种新型的pH响应合成遗传控制器解决了这个问题，该控制器使用一种称为CadCΔ的修饰的跨膜转录因子。测试了该遗传回路检测细胞外pH值和控制培养基中D-木糖醛酸积累的能力。结果表明，pH响应型遗传传感器可赋予D-木糖醛酸积累动态调节功能，该功能可随着培养基pH值的扰动而调节。这是第一份证明使用pH响应跨膜转录因子作为专为XOP设计的合成遗传电路中的传感器的报告。这可以作为开发涉及酸性中间体的类似途径的其他遗传控制器的基准。