Abstract

Genes involved in the transport and catabolism of carbohydrates are usually controlled through the binding of the catabolite control protein A (CcpA) to the catabolite-responsive elements (cre) of target genes in Gram-positive bacteria. In this work, we show how the elimination of the cre sites in Lactobacillus casei BL23 promoters induced by sorbitol (PgutF), maltose (PmalL), and myo-inositol (PiolT) allowed the induction of gene expression in media supplemented with sorbitol, maltose, and myo-inositol, respectively, even in the presence of glucose. This was studied using plasmids encoding the anaerobic fluorescent protein evoglow-Pp1 as a reporter. In addition, gutF cre site was introduced into a bile inducible promoter (P16090) and into the constitutive promoter of the elongation factor P (PEf-P) of L. casei BL23. The existence of the cre site blocked gene expression in the P16090 inducible promoter in the presence of glucose, while it had no influence on the expression of the PEf-P constitutive one. These results demonstrated that the introduction or elimination of cre sites in inducible promoters allows the control and modification of their heterologous genetic expression, showing how the cre site, the transcriptional regulator, and CcpA interact to control gene expression in inducible genes.

Key points

• Cre sequences regulate gene expression in inducible promoters in L. casei BL23.

• Cre sites do not affect gene expression in constitutive promoters in L. casei BL23.

• Cre sequences could control heterologous genic expression in lactobacilli.

中文翻译：

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分解代谢物响应元件作为控制乳酸菌中异源基因表达的策略

摘要

通常，通过分解代谢物控制蛋白A（CcpA）与革兰氏阳性细菌中靶基因的分解代谢物响应元件（cre）的结合来控制与碳水化合物的运输和分解代谢有关的基因。在这项工作中，我们展示了山梨糖醇（P gut F），麦芽糖（P mal L）和肌醇（P iol T）诱导的干酪乳杆菌BL23启动子中cre位点的消除如何诱导基因表达。即使在存在葡萄糖的情况下，也分别补充有山梨糖醇，麦芽糖和肌醇的培养基。使用编码厌氧荧光蛋白evoglow-Pp1的质粒作为报告基因进行了研究。另外，肠˚FCRE点被引入到胆汁诱导型启动子（P16090）并进入延伸因子P（P的组成型启动子EF-的P）干酪乳杆菌BL23。cre位点的存在在葡萄糖存在下阻止了P16090诱导型启动子中的基因表达，而对P Ef- P组成型表达没有影响。这些结果证明，在诱导型启动子中引入或消除cre位点可以控制和修饰其异源基因表达，显示了cre位点，转录调节子和CcpA如何相互作用以控制诱导型基因中的基因表达。

关键点

•Cre序列调节干酪乳杆菌BL23中诱导型启动子中的基因表达。

•Cre位点不影响干酪乳杆菌BL23组成型启动子中的基因表达。

•Cre序列可以控制乳杆菌中的异源基因表达。