Catabolite responsive elements as a strategy for the control of heterologous gene expression in lactobacilli
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APPLIED GENETICS AND MOLECULAR BIOTECHNOLOGY
Catabolite responsive elements as a strategy for the control of heterologous gene expression in lactobacilli Susana Langa 1
&
Ángela Peirotén 1 & Juan Luis Arqués 1 & José María Landete 1
Received: 13 October 2020 / Revised: 28 October 2020 / Accepted: 8 November 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
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 myoinositol (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. Keywords catabolite response element . inducible promoter . constitutive promoter . genic expression . Lactobacillus
Introduction As a general trend, the use of a strong and constitutive promoter is considered for a high yield heterologous gene expression. However, in most cases, this type of promoter does not provide the desired effect since the resources for the normal growth of the cells may be compromised as the result of the high level of expression of the gene of interest. This is especially important when the foreign protein has a negative effect for the host cell. Therefore, it is advisable to use adjustable promoters instead, with the capacity of being “switched on and off” when required. Lactic acid bacteria (LAB) are very * Susana Langa [email protected] 1
Departamento de Tecnología de Alimentos, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Carretera de La Coruña Km 7.5, 28040 Madrid, Spain
interesting from the biotechnological point of view because of their safe status and the probiotic and/or antimicrobial properties attributed to some of
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