title: Repression of the pyr operon in Lactobacillus plantarum prevents its ability to grow at low carbon dioxide levels.
abstract: Carbamoyl phosphate is a precursor for both arginine and pyrimidine biosynthesis. In Lactobacillus plantarum, carbamoyl phosphate is synthesized from glutamine, ATP, and carbon dioxide by two sets of identified genes encoding carbamoyl phosphate synthase (CPS). The expression of the carAB operon (encoding CPS-A) responds to arginine availability, whereas pyrAaAb (encoding CPS-P) is part of the pyrR1BCAaAbDFE operon coding for the de novo pyrimidine pathway repressed by exogenous uracil. The pyr operon is regulated by transcription attenuation mediated by a trans-acting repressor that binds to the pyr mRNA attenuation site in response to intracellular UMP/phosphoribosyl pyrophosphate pools. Intracellular pyrimidine triphosphate nucleoside pools were lower in mutant FB335 (carAB deletion) harboring only CPS-P than in the wild-type strain harboring both CPS-A and CPS-P. Thus, CPS-P activity is the limiting step in pyrimidine synthesis. FB335 is unable to grow in the presence of uracil due to a lack of sufficient carbamoyl phosphate required for arginine biosynthesis. Forty independent spontaneous FB335-derived mutants that have lost regulation of the pyr operon were readily obtained by their ability to grow in the presence of uracil and absence of arginine; 26 harbored mutations in the pyrR1-pyrB loci. One was a prototroph with a deletion of both pyrR1 and the transcription attenuation site that resulted in large amounts of excreted pyrimidine nucleotides and increased intracellular UTP and CTP pools compared to wild-type levels. Low pyrimidine-independent expression of the pyr operon was obtained by antiterminator site-directed mutagenesis. The resulting AE1023 strain had reduced UTP and CTP pools and had the phenotype of a high-CO2-requiring auxotroph, since it was able to synthesize sufficient arginine and pyrimidines only in CO2-enriched air. Therefore, growth inhibition without CO2 enrichment may be due to low carbamoyl phosphate pools from lack of CPS activity.
authors.affiliation: Laboratoire de Dynamique, Evolution et Expression de Génomes de Microorganismes, Université Louis Pasteur/CNRS FRE 2326, 28 rue Goethe, F-67083 Strasbourg, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Nicoloff
authors.forename: Aram
authors.initials: A
authors.lastname: Elagöz
authors.forename: Florence
authors.initials: F
authors.lastname: Arsène-Ploetze
authors.forename: Benoît
authors.initials: B
authors.lastname: Kammerer
authors.forename: Jan
authors.initials: J
authors.lastname: Martinussen
authors.forename: Françoise
authors.initials: F
authors.lastname: Bringel
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing) / Q000378:metabolism; D002221:Carbamyl Phosphate / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D048191:Lactiplantibacillus plantarum / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D009705:Nucleosides / Q000378:metabolism; D009876:Operon / Q000502:physiology*; D010430:Pentosyltransferases / Q000235:genetics* / Q000378:metabolism; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D009705:Nucleosides; D012329:RNA, Bacterial; D012097:Repressor Proteins; D002245:Carbon Dioxide; D002221:Carbamyl Phosphate; D010430:Pentosyltransferases; C098851:PyrR protein, bacteria; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing)
references.citation: Proc Natl Acad Sci U S A. 2003 Feb 18;100(4):1990-5
references.pmid: 12566566
references.citation: J Bacteriol. 2003 Mar;185(5):1503-8
references.pmid: 12591866
references.citation: J Bacteriol. 2003 Aug;185(16):4764-71
references.pmid: 12896995
references.citation: Appl Environ Microbiol. 2003 Oct;69(10):6032-40
references.pmid: 14532059
references.citation: J Bacteriol. 1974 Dec;120(3):1370-9
references.pmid: 4373439
references.citation: FEMS Microbiol Lett. 1990 Jun 1;57(3):233-8
references.pmid: 2210335
references.citation: J Gen Microbiol. 1991 Oct;137(10):2387-94
references.pmid: 1722815
references.citation: J Bacteriol. 1994 Jun;176(12):3708-22
references.pmid: 8206849
references.citation: J Bacteriol. 1995 Jan;177(1):271-4
references.pmid: 7798145
references.citation: J Bacteriol. 1995 Mar;177(5):1315-25
references.pmid: 7868607
references.citation: FEMS Microbiol Lett. 1996 Mar 15;137(1):13-8
references.pmid: 8935652
references.citation: Gene. 1996 Dec 5;182(1-2):37-43
references.pmid: 8982065
references.citation: J Bacteriol. 1997 Apr;179(8):2658-67
references.pmid: 9098065
references.citation: J Bacteriol. 1997 Apr;179(8):2697-706
references.pmid: 9098069
references.citation: Structure. 1998 Mar 15;6(3):337-50
references.pmid: 9551555
references.citation: Prog Nucleic Acid Res Mol Biol. 1999;62:329-67
references.pmid: 9932459
references.citation: J Bacteriol. 1999 Feb;181(4):1324-9
references.pmid: 9973361
references.citation: J Bacteriol. 2000 Jun;182(12):3416-22
references.pmid: 10852872
references.citation: J Bacteriol. 2001 May;183(9):2785-94
references.pmid: 11292797
references.citation: Nucleic Acids Res. 2001 Dec 1;29(23):4851-65
references.pmid: 11726695
references.citation: J Bacteriol. 2002 May;184(9):2521-8
references.pmid: 11948166
references.citation: Appl Environ Microbiol. 2003 May;69(5):2674-83
references.pmid: 12732536