Transcriptome profiling of Lactococcus lactis subsp. cremoris CECT 8666 in response to agmatine

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Lactococcus lactis subsp. cremoris CECT 8666 synthesizes putrescine from agmatine via the agmatine deiminase (AGDI) pathway.
• The AGDI pathway involves a five-gene cluster (aguR, aguB, aguD, aguA, aguC) in L. lactis.
• The aguBDAC operon encodes proteins for agmatine uptake and conversion, regulated by the aguR gene product.

Purpose of the Study:

• To investigate the transcriptional regulation of the AGDI pathway in L. lactis subsp. cremoris CECT 8666.
• To understand how agmatine and carbon sources influence gene expression within the AGDI cluster.

Main Methods:

• Transcriptional profiling of L. lactis subsp. cremoris CECT 8666.
• Culturing the strain in M17 medium with galactose as the carbon source, with and without agmatine supplementation.
• Analyzing gene expression data for agmatine-regulated genes.

Main Results:

• The aguBDAC operon is transcriptionally activated by agmatine.
• Carbon catabolite repression (CCR) by glucose affects aguBDAC operon transcription, but not by lactose or galactose.
• The aguR regulatory gene is not regulated by CCR or agmatine.

Conclusions:

• Agmatine concentration directly influences the expression of the aguBDAC catabolic operon.
• Galactose as a carbon source does not induce carbon catabolite repression on the AGDI pathway.
• The aguR gene acts as an independent regulator of the agmatine deiminase pathway.