Dataset Information

Uracil salvage pathway in Lactobacillus plantarum: Transcription and genetic studies.

ABSTRACT: The uracil salvage pathway in Lactobacillus plantarum was demonstrated to be dependent on the upp-pyrP gene cluster. PyrP was the only high-affinity uracil transporter since a pyrP mutant no longer incorporated low concentrations of radioactively labeled uracil and had increased resistance to the toxic uracil analogue 5-fluorouracil. The upp gene encoded a uracil phosphoribosyltransferase (UPRT) enzyme catalyzing the conversion of uracil and 5-phosphoribosyl-alpha-1-pyrophosphate to UMP and pyrophosphate. Analysis of mutants revealed that UPRT is a major cell supplier of UMP synthesized from uracil provided by preformed nucleic acid degradation. In a mutant selection study, seven independent upp mutants were isolated and all were found to excrete low amounts of pyrimidines to the growth medium. Pyrimidine-dependent transcription regulation of the biosynthetic pyrimidine pyrR1-B-C-Aa1-Ab1-D-F-E operon was impaired in the upp mutants. Despite the fact that upp and pyrP are positioned next to each other on the chromosome, they are not cotranscribed. Whereas pyrP is expressed as a monocistronic message, the upp gene is part of the lp_2376-glyA-upp operon. The lp_2376 gene encodes a putative protein that belongs to the conserved protein family of translation modulators such as Sua5, YciO, and YrdC. The glyA gene encodes a putative hydroxymethyltransferase involved in C1 unit charging of tetrahydrofolate, which is required in the biosynthesis of thymidylate, pantothenate, and purines. Unlike upp transcription, pyrP transcription is regulated by exogenous pyrimidine availability, most likely by the same mechanism of transcription attenuation as that of the pyr operon.

SUBMITTER: Arsene-Ploetze F

PROVIDER: S-EPMC1483017 | biostudies-literature | 2006 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Uracil salvage pathway in Lactobacillus plantarum: Transcription and genetic studies.

Arsène-Ploetze Florence F Nicoloff Hervé H Kammerer Benoît B Martinussen Jan J Bringel Françoise F

Journal of bacteriology 20060701 13

The uracil salvage pathway in Lactobacillus plantarum was demonstrated to be dependent on the upp-pyrP gene cluster. PyrP was the only high-affinity uracil transporter since a pyrP mutant no longer incorporated low concentrations of radioactively labeled uracil and had increased resistance to the toxic uracil analogue 5-fluorouracil. The upp gene encoded a uracil phosphoribosyltransferase (UPRT) enzyme catalyzing the conversion of uracil and 5-phosphoribosyl-alpha-1-pyrophosphate to UMP and pyro ...[more]

PMID: 16788187

Similar Datasets

Project description:Heat stress resistance and response were studied in strains of Lactobacillus plantarum. Stationary-phase cells of L. plantarum DPC2739 had decimal reduction times (D values) (D value was the time that it took to reduce the number of cells by 1 log cycle) in sterile milk of 32.9, 14.7, and 7.14 s at 60, 72, and 75 degrees C, respectively. When mid-exponential-phase cells were used, the D values decreased. The temperature increases which caused a 10-fold reduction in the D value ranged from 9 to 20 degrees C, depending on the strain. Part of the cell population treated at 72 degrees C for 90 s recovered viability during incubation at 7 degrees C in sterile milk for 20 days. When mid-exponential- or stationary-phase cells of L. plantarum DPC2739 were adapted to 42 degrees C for 1 h, the heat resistance at 72 degrees C for 90 s increased ca. 3 and 2 log cycles, respectively. Heat-adapted cells also showed increased growth at pH 5 and in the presence of 6% NaCl. Two-dimensional gel electrophoresis of proteins expressed by control and heat-adapted cells revealed changes in the levels of expression of 31 and 18 proteins in mid-exponential- and stationary-phase cells, respectively. Twelve proteins were commonly induced. Nine proteins induced in the heat-adapted mid-exponential- and/or stationary-phase cells of L. plantarum DPC2739 were subjected to N-terminal sequencing. These proteins were identified as DnaK, GroEL, trigger factor, ribosomal proteins L1, L11, L31, and S6, DNA-binding protein II HlbA, and CspC. All of these proteins have been found to play a role in the mechanisms of stress adaptation in other bacteria. Antibodies against GroES detected a protein which was induced moderately, while antibodies against DnaJ and GrpE reacted with proteins whose level of expression did not vary after heat adaptation. This study showed that the heat resistance of L. plantarum is a complex process involving proteins with various roles in cell physiology, including chaperone activity, ribosome stability, stringent response mediation, temperature sensing, and control of ribosomal function. The physiological mechanisms of response to pasteurization in L. plantarum are fundamental for survival in cheese during manufacture.

Project description:Lactobacillus plantarum is the lactic acid bacterial species most frequently found in plant-food fermentations where hydroxycinnamic acids are abundant. L. plantarum efficiently decarboxylates these compounds and also reduces them, yielding substituted phenylpropionic acids. Although the reduction step is known to be induced by a hydroxycinnamic acid, the enzymatic machinery responsible for this reduction pathway has not been yet identified and characterized. A previous study on the transcriptomic response of L. plantarum to p-coumaric acid revealed a marked induction of two contiguous genes, lp_1424 and lp_1425, encoding putative reductases. In this work, the disruption of these genes abolished the hydroxycinnamate reductase activity of L. plantarum, supporting their involvement in such chemical activity. Functional in vitro studies revealed that Lp_1425 (HcrB) exhibits hydroxycinnamate reductase activity but was unstable in solution. In contrast, Lp_1424 (HcrA) was inactive but showed high stability. When the hcrAB genes were co-overexpressed, the formation of an active heterodimer (HcrAB) was observed. Since L. plantarum reductase activity was only observed on hydroxycinnamic acids (o-coumaric, m-coumaric, p-coumaric, caffeic, ferulic, and sinapic acids), the presence of a hydroxyl group substituent on the benzene ring appears to be required for activity. In addition, hydroxycinnamate reductase activity was not widely present among lactic acid bacteria, and it was associated with the presence of hcrAB genes. This study revealed that L. plantarum hydroxycinnamate reductase is a heterodimeric NADH-dependent coumarate reductase acting on a carbon-carbon double bond.IMPORTANCELactobacillus plantarum is a bacterial species frequently found in the fermentation of vegetables where hydroxycinnamic acids are present. The bacterial metabolism on these compounds during fermentation plays a fundamental role in the biological activity of hydroxycinnamates. L. plantarum strains exhibit an as yet unknown reducing activity, transforming hydroxycinnamates to substituted phenylpropionic acids, which possess higher antioxidant activity than their precursors. The protein machinery involved in hydroxycinnamate reduction, HcrAB, was genetically identified and characterized. The heterodimeric NADH-dependent coumarate reductase HcrAB described in this work provides new insights on the L. plantarum metabolic response to counteract the stressful conditions generated by food phenolics.

Dataset Information

Uracil salvage pathway in Lactobacillus plantarum: Transcription and genetic studies.

Publications

Uracil salvage pathway in Lactobacillus plantarum: Transcription and genetic studies.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets