AguR, a Transmembrane Transcription Activator of the Putrescine Biosynthesis Operon in Lactococcus lactis, Acts in Response to the Agmatine Concentration

Dairy industry fermentative processes mostly use Lactococcus lactis as a starter. However, some dairy L. lactis strains produce putrescine, a biogenic amine that raises food safety and spoilage concerns, via the agmatine deiminase (AGDI) pathway. The enzymatic activities responsible for putrescine b...

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Bibliographic Details
Published in:Applied and environmental microbiology 2015-09, Vol.81 (18), p.6145-6157
Main Authors: Linares, Daniel M, Del Rio, Beatriz, Redruello, Begoña, Ladero, Victor, Martin, M Cruz, de Jong, Anne, Kuipers, Oscar P, Fernandez, Maria, Alvarez, Miguel A
Format: Article
Language:English
Subjects:
Agmatine - metabolism
Biosynthetic Pathways - genetics
Dairy industry
Deoxyribonucleic acid
DNA
Food Microbiology
Food safety
Gene Expression Profiling
Gene Expression Regulation, Bacterial
Lactococcus lactis - genetics
Lactococcus lactis - metabolism
Operon
Probiotics
Proteins
Putrescine - biosynthesis
Signal transduction
Trans-Activators - genetics
Trans-Activators - metabolism
Transcription, Genetic
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Summary:Dairy industry fermentative processes mostly use Lactococcus lactis as a starter. However, some dairy L. lactis strains produce putrescine, a biogenic amine that raises food safety and spoilage concerns, via the agmatine deiminase (AGDI) pathway. The enzymatic activities responsible for putrescine biosynthesis in this bacterium are encoded by the AGDI gene cluster. The role of the catabolic genes aguB, aguD, aguA, and aguC has been studied, but knowledge regarding the role of aguR (the first gene in the cluster) remains limited. In the present work, aguR was found to be a very low level constitutively expressed gene that is essential for putrescine biosynthesis and is transcribed independently of the polycistronic mRNA encoding the catabolic genes (aguBDAC). In response to agmatine, AguR acts as a transcriptional activator of the aguB promoter (PaguB), which drives the transcription of the aguBDAC operon. Inverted sequences required for PaguB activity were identified by deletion analysis. Further work indicated that AguR is a transmembrane protein which might function as a one-component signal transduction system that senses the agmatine concentration of the medium and, accordingly, regulates the transcription of the aguBDAC operon through a C-terminal cytoplasmic DNA-binding domain typically found in LuxR-like proteins.
ISSN:0099-2240
1098-5336
DOI:10.1128/AEM.00959-15