Metabolic engineering and synthetic biology usually require universal expression systems for stable and efficient gene expression in various organisms. In this study, a host-independent and stable T7 expression system had been developed by integrating T7 RNA polymerase and its cognate transcriptional units in single plasmid. The expression of T7 RNA polymerase was restricted below its lethal threshold using a T7 RNA polymerase antisense gene cassette, which allowed long periods of cultivation and protein production. In addition, by designing ribosome binding sites, we further tuned the expression capacity of this novel T7 system within a wide range. This host-independent expression system efficiently expressed genes in five different Gram-negative strains and one Gram-positive strain and was also shown to be applicable in a real industrial d-p-hydroxyphenylglycine production system.

中文翻译：

---

整合T7 RNA聚合酶及其同源转录单位在单个质粒中的宿主独立和稳定表达系统。

代谢工程和合成生物学通常需要通用的表达系统，才能在各种生物中稳定有效地表达基因。在这项研究中，通过将T7 RNA聚合酶及其同源转录单位整合到单个质粒中，开发了独立于宿主且稳定的T7表达系统。使用T7 RNA聚合酶反义基因盒将T7 RNA聚合酶的表达限制在其致死阈值以下，从而可以长期培养和生产蛋白质。另外，通过设计核糖体结合位点，我们进一步在宽范围内调节了该新型T7系统的表达能力。这种独立于宿主的表达系统可以在五种不同的革兰氏阴性菌株和一种革兰氏阳性菌株中高效表达基因，并且还显示出可用于实际的工业生产中。d - p -hydroxyphenylglycine生产体系。