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The pyrimidine operon pyrRPB-carA from Lactococcus lactis
J Martinussen1, J Schallert, B Andersen
1Department of Microbiology, The Technical University of Denmark, DK-2800 Lyngby, Denmark. imjm@pop.dtu.dk
Journal of Bacteriology
|April 9, 2001
Summary
This study identifies a pyrimidine operon in Lactococcus lactis, detailing the functions of pyrR, pyrP, pyrB, and carA genes. The pyrR gene regulates pyrimidine biosynthesis, essential for cell growth.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Lactococcus lactis is a key lactic acid bacterium with complex metabolic pathways.
- Understanding pyrimidine biosynthesis is crucial for bacterial growth and metabolism.
Purpose of the Study:
- To identify and characterize the pyrimidine operon in Lactococcus lactis subsp. lactis MG1363.
- To elucidate the functions of the genes pyrR, pyrP, pyrB, and carA within this operon.
Main Methods:
- Mutational analysis was employed to determine gene functions.
- Gene expression was studied at the transcriptional level.
Main Results:
- A four-gene operon (pyrR, pyrP, pyrB, carA) involved in pyrimidine biosynthesis was identified.
- PyrR functions as a regulatory gene controlling pyrimidine gene expression.
- PyrP acts as a uracil permease for exogenous uracil uptake.
- PyrB and CarA encode key enzymes in pyrimidine biosynthesis; CarA is also vital for arginine synthesis.
Conclusions:
- The pyrRPB-carA operon is transcriptionally regulated, likely via an attenuation mechanism involving the PyrR protein.
- This operon plays a critical role in pyrimidine and, for carA, arginine metabolism in Lactococcus lactis.