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Jian P, Liu J, Li L, Song Q, Zhang D, Zhang S, Chai C, Zhao H, Zhao G, Zhu H, Qiao J. AcrR1, a novel TetR/AcrR family repressor, mediates acid and antibiotic resistance and nisin biosynthesis in Lactococcus lactis F44. J Dairy Sci 2024; 107:6576-6591. [PMID: 38762103 DOI: 10.3168/jds.2024-24754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 03/31/2024] [Indexed: 05/20/2024]
Abstract
Lactococcus lactis, widely used in the manufacture of dairy products, encounters various environmental stresses both in natural habitats and during industrial processes. It has evolved intricate machinery of stress sensing and defense to survive harsh stress conditions. Here, we identified a novel TetR/AcrR family transcription regulator, designated AcrR1, to be a repressor for acid and antibiotic tolerance that was derepressed in the presence of vancomycin or under acid stress. The survival rates of acrR1 deletion strain ΔAcrR1 under acid and vancomycin stresses were about 28.7-fold (pH 3.0, HCl), 8.57-fold (pH 4.0, lactic acid) and 2.73-fold (300 ng/mL vancomycin) greater than that of original strain F44. We also demonstrated that ΔAcrR1 was better able to maintain intracellular pH homeostasis and had a lower affinity to vancomycin. No evident effects of AcrR1 deletion on the growth and morphology of strain F44 were observed. Subsequently, we characterized that the transcription level of genes associated with amino acids biosynthesis, carbohydrate transport and metabolism, multidrug resistance, and DNA repair proteins significantly upregulated in ΔAcrR1 using transcriptome analysis and quantitative reverse transcription-PCR assays. Additionally, AcrR1 could repress the transcription of the nisin post-translational modification gene, nisC, leading to a 16.3% increase in nisin yield after AcrR1 deletion. Our results not only refined the knowledge of the regulatory mechanism of TetR/AcrR family regulator in L. lactis, but presented a potential strategy to enhance industrial production of nisin.
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Affiliation(s)
- Pingqiu Jian
- Department of Pharmaceutical and Biological Engineering, School of Chemical Engineering, Sichuan University, 610047 Chengdu, China
| | - Jiaheng Liu
- Department of Pharmaceutical and Biological Engineering, School of Chemical Engineering, Sichuan University, 610047 Chengdu, China.
| | - Li Li
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, 300072 Tianjin, China
| | - Qianqian Song
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, 300072 Tianjin, China
| | - Di Zhang
- Department of Pharmaceutical and Biological Engineering, School of Chemical Engineering, Sichuan University, 610047 Chengdu, China
| | - Shenyi Zhang
- Department of Pharmaceutical and Biological Engineering, School of Chemical Engineering, Sichuan University, 610047 Chengdu, China
| | - Chaofan Chai
- Department of Pharmaceutical and Biological Engineering, School of Chemical Engineering, Sichuan University, 610047 Chengdu, China
| | - Hui Zhao
- Department of Pharmaceutical and Biological Engineering, School of Chemical Engineering, Sichuan University, 610047 Chengdu, China
| | - Guangrong Zhao
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, 300072 Tianjin, China
| | - Hongji Zhu
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, 300072 Tianjin, China
| | - Jianjun Qiao
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, 300072 Tianjin, China
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Song Q, Wu H, Zhang P, Zhu H, Xie J, Liu J, Qiao J. The MarR family regulator RmaH mediates acid tolerance of Lactococcus lactis through regulating peptidoglycan modification genes. J Dairy Sci 2024:S0022-0302(24)01078-6. [PMID: 39154730 DOI: 10.3168/jds.2024-25152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2024] [Accepted: 07/22/2024] [Indexed: 08/20/2024]
Abstract
Lactococcus lactis, widely used in the food fermentation industry, has developed various ways to regulate acid adaptation in the process of evolution. The investigation into how peptidoglycan (PG) senses and responds to acid stress is an expanding field. Here, we addressed the regulation of murT-gatD genes which are responsible for the amidation of PG D-Glu. We found that lactic acid stress reduced murT-gatD expression, and overexpressing these genes notably decreased acid tolerance of L. lactis NZ9000, possibly due to a reduction in PG's negative charge, facilitating the influx of extracellular protons into the cell. Subsequently, using a combination of DNA pull-down assay and electrophoretic mobility shift assay (EMSA), we identified a novel MarR family regulator, RmaH, as an activator of murT-gatD transcription. Further MEME motif prediction, EMSA verification and fluorescent protein reporter assay showed that RmaH directly bound to the DNA motif 5'-KGVAWWTTTTGCT-3' located in the upstream region of murT-gatD. Beyond the mechanistic investigation of RmaH activation of murT-gatD, this study provides new insight into how peptidoglycan modification is regulated and responds to lactic acid stress.
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Affiliation(s)
- Qianqian Song
- Department of Pharmaceutical and Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu, China
| | - Hao Wu
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China;; Zhejiang Shaoxing research institute of Tianjin University, Shaoxing, 312300, China
| | - Peng Zhang
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Hongji Zhu
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Jiawei Xie
- Institute of New Energy and Low-Carbon Technology, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, 610065, China
| | - Jiaheng Liu
- Department of Pharmaceutical and Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu, China.
| | - Jianjun Qiao
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China;; Zhejiang Shaoxing research institute of Tianjin University, Shaoxing, 312300, China;; Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjian 300072, China;; SynBio Research Platform Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China.
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Toussaint F, Henry de Frahan M, Poncelet F, Ladrière JM, Horvath P, Fremaux C, Hols P. Unveiling the regulatory network controlling natural transformation in lactococci. PLoS Genet 2024; 20:e1011340. [PMID: 38950059 PMCID: PMC11244767 DOI: 10.1371/journal.pgen.1011340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 07/12/2024] [Accepted: 06/13/2024] [Indexed: 07/03/2024] Open
Abstract
Lactococcus lactis is a lactic acid bacterium of major importance for food fermentation and biotechnological applications. The ability to manipulate its genome quickly and easily through competence for DNA transformation would accelerate its general use as a platform for a variety of applications. Natural transformation in this species requires the activation of the master regulator ComX. However, the growth conditions that lead to spontaneous transformation, as well as the regulators that control ComX production, are unknown. Here, we identified the carbon source, nitrogen supply, and pH as key factors controlling competence development in this species. Notably, we showed that these conditions are sensed by three global regulators (i.e., CcpA, CodY, and CovR), which repress comX transcription directly. Furthermore, our systematic inactivation of known signaling systems suggests that classical pheromone-sensing regulators are not involved. Finally, we revealed that the ComX-degrading MecA-ClpCP machinery plays a predominant role based on the identification of a single amino-acid substitution in the adaptor protein MecA of a highly transformable strain. Contrasting with closely-related streptococci, the master competence regulator in L. lactis is regulated both proximally by general sensors and distantly by the Clp degradation machinery. This study not only highlights the diversity of regulatory networks for competence control in Gram-positive bacteria, but it also paves the way for the use of natural transformation as a tool to manipulate this biotechnologically important bacterium.
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Affiliation(s)
- Frédéric Toussaint
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Marie Henry de Frahan
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Félix Poncelet
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Jean-Marc Ladrière
- IFF Health & Biosciences, Danisco France SAS, Dangé-Saint-Romain, France
| | - Philippe Horvath
- IFF Health & Biosciences, Danisco France SAS, Dangé-Saint-Romain, France
| | - Christophe Fremaux
- IFF Health & Biosciences, Danisco France SAS, Dangé-Saint-Romain, France
| | - Pascal Hols
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, Louvain-la-Neuve, Belgium
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Wu H, Zhang Y, Li L, Li Y, Yuan L, E Y, Qiao J. Positive regulation of the DLT operon by TCSR7 enhances acid tolerance of Lactococcus lactis F44. J Dairy Sci 2022; 105:7940-7950. [PMID: 36028342 DOI: 10.3168/jds.2022-21898] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 05/14/2022] [Indexed: 11/19/2022]
Abstract
Lactococcus lactis, a lactic acid bacterium, has been widely used in the fermented dairy products. The acid tolerance of L. lactis is of great importance to food fermentation and probiotic applications. As the first barrier of bacteria, the cell wall has a protective effect on strains under many stress conditions, whereas the regulatory mechanism has rarely been reported. Here, based on the transcription analysis of 9 cell wall or membrane-related genes of L. lactis F44 under acid stress, the transcription levels of DACB, DLTD, YLBA, HRTA, WP_080613266.1 (1610), and ERFK genes were significantly increased. We constructed 9 overexpressing strains with the cell wall or membrane-related genes, respectively. It was demonstrated that the survival rates under acid stress of DACB, DLTD, and ERFK were significantly higher than that of wild-type F44. To investigate the regulatory mechanism, a DNA pull-down assay was used to identify the transcriptional regulators of these 3 genes. It was discovered that the 2-component system (TCS) transcriptional regulator TCSR7 bound to the upstream region of DLTD involved in the teichoic acid (TA) alanylation. The combination was confirmed through an electrophoretic mobility shift assay in vitro. Reverse-transcription quantitative PCR results indicated that TCSR7 upregulated the expression of DLTD gene. In addition, the transcription level of TCSR7 increased approximately 1.8-fold (log2 fold change) under acidic conditions. In summary, this study found that TCSR7 was induced by acid stress to upregulate the transcription level of the DLT operon genes, which might increase the positive charge on the cell membrane surface to increase the acid tolerance of the strain. This study lays the foundation for the regulatory mechanism of TA alanylation under acid stress.
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Affiliation(s)
- Hao Wu
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China; Zhejiang Shaoxing Research Institute of Tianjin University, Shaoxing 312300, P. R. China
| | - Yangling Zhang
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China
| | - Li Li
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China; Zhejiang Shaoxing Research Institute of Tianjin University, Shaoxing 312300, P. R. China; Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, P. R. China; SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, P. R. China
| | - Yanni Li
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China
| | - Lin Yuan
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China; Department of Bioengineering, School of Food Science and Bioengineering, Tianjin Agricultural University, Tianjin 300072, P. R. China
| | - Yue E
- Zhejiang Shaoxing Research Institute of Tianjin University, Shaoxing 312300, P. R. China
| | - Jianjun Qiao
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China; Zhejiang Shaoxing Research Institute of Tianjin University, Shaoxing 312300, P. R. China; Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, P. R. China; SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, P. R. China.
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