Regulation of Enzyme Synthesis in the Arginine Biosynthetic Pathway of Pseudomonas aeruginosa

Voellmy, Richard; Leisinger, Th.

doi:10.1099/00221287-109-1-25

Cited by 26 publications

(39 citation statements)

References 20 publications

(8 reference statements)

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“…The only exception is argD, which is the same gene as the arginineinducible aruC gene of the AST pathway (11,18). These results were consistent with the conclusions of earlier reports (12,17,49).…”

Section: Identification Of Argr-regulated Genessupporting

confidence: 82%

“…Exogenous agmatine but not arginine induced these genes (14,29). Very little is known about the enzymes or genes of the ADH pathway; only the gbuA gene and the bifunctional kauB gene have been characterized (32).For arginine biosynthesis, only the argF gene and the carAB operon, which encode ornithine carbamoyltransferase and carbamoylphosphate synthetase, respectively, have been reported to be repressible by arginine (1,17,19,49).With the completion of the Pseudomonas Genome Project and the use of innovative DNA microarray technology (42), it has become feasible to identify and characterize genes of metabolic pathways in a very efficient and systematic way. Considering the relatively large size of the P. aeruginosa genome and its reputation as a metabolically versatile organism, it is very likely that many "hypothetical" or "unknown" genes encode catabolic enzymes for the utilization of different nutrients that this organism encounters in its varied habitats.…”

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confidence: 99%

“…For arginine biosynthesis, only the argF gene and the carAB operon, which encode ornithine carbamoyltransferase and carbamoylphosphate synthetase, respectively, have been reported to be repressible by arginine (1,17,19,49).…”

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Transcriptome Analysis of the ArgR Regulon inPseudomonas aeruginosa

Yang

2004

J Bacteriol

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Arginine metabolism in pseudomonads with multiple catabolic pathways for its utilization as carbon and nitrogen sources is of particular interest as the model system to study control of metabolic integration. We performed transcriptome analyses to identify genes controlled by the arginine regulatory protein ArgR and to better understand arginine metabolic pathways of P. aeruginosa. We compared gene expression in wild-type strain PAO1 with that in argR mutant strain PAO501 grown in glutamate minimal medium in the presence and absence of arginine. Ten putative transcriptional units of 28 genes were inducible by ArgR and arginine, including all known ArgR-regulated operons under aerobic conditions. The newly identified genes include the putative adcAB operon, which encodes a catabolic arginine decarboxylase and an antiporter protein, and PA0328, which encodes a hypothetical fusion protein of a peptidase and a type IV autotransporter. Also identified as members of the arginine network are the following solute transport systems: PA1971 (braZ) for branched-chain amino acids permease; PA2042 for a putative sodium:serine symporter; PA3934, which belongs to the family of small oligopeptide transporters; and PA5152-5155, which encodes components of an ABC transporter for a putative opine uptake system. The effect of arginine on the expression of these genes was confirmed by lacZ fusion studies and by DNA binding studies with purified ArgR. Only five transcriptional units of nine genes were qualified as repressible by ArgR and arginine, with three operons (argF, carAB, and argG) in arginine biosynthesis and two operons (gltBD and gdhA) in glutamate biosynthesis. These results indicate that ArgR is important in control of arginine and glutamate metabolism and that arginine and ArgR may have a redundant effect in inducing the uptake systems of certain compounds.Pseudomonas aeruginosa possesses four different catabolic pathways for utilization of arginine (11): the arginine deiminase (ADI) pathway, the arginine succinyltransferase (AST) pathway, the arginine decarboxylase (ADC) pathway, and the arginine dehydrogenase (ADH) pathway (Fig. 1). Under aerobic conditions, Haas and coworkers have established that arginine utilization occurs mainly through the AST pathway, which converts arginine to glutamate (20,43). Recent studies in the laboratories of Lu and Abdelal have shown that the aru operon, which encodes the AST pathway, and the gdhB gene, which encodes a catabolic glutamate dehydrogenase, are inducible by arginine and that this effect is mediated by ArgR (18,24). In P. aeruginosa, ArgR, the arginine-responsive regulator protein, is autoinduced from the aot-argR operon for arginine uptake and regulation (35). The ArgR protein of P. aeruginosa belongs to the AraC/XylS family of transcriptional regulators (7) and is thus quite different in structure and function from the ArgR proteins of enteric bacteria and Bacillus subtilis (3,4,6,23,25), which have a high degree of similarity in their three-dimensional structures and DNA...

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Section: Identification Of Argr-regulated Genessupporting

confidence: 82%

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confidence: 99%

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Transcriptome Analysis of the ArgR Regulon inPseudomonas aeruginosa

Yang

2004

J Bacteriol

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“…Several enzymes of arginine biosynthesis are also not affected by arginine limitation or excess [24]. The anabolic ornithine carbamyltransferase is the only arginine biosynthetic enzyme subject to significant repression [25].…”

Section: Discussionmentioning

confidence: 99%

Carbamoylphosphate Synthetase from Pseudomonas aeruginosa

Abdelal¹,

Bussey²,

Vickers³

1983

European Journal of Biochemistry

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Carbamoylphosphate synthetase from Pseudomonas ueruginosa is subject to repression by pyrimidines and significant derepression by limitation of arginine or pyrimidines. Carbamoylphosphate synthetase was purified to homogeneity from a derepressed strain of P. aeruginosa. The molecular weight of the enzyme was estimated to be 168 000 by sucrose gradient ultracentrifugation. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate showed that the enzyme is composed of two non-identical subunits with molecular weights of 122000 and 44000. Cross-linking the enzyme prior to electrophoresis yielded an additional band corresponding to a molecular weight of 165000, showing that the enzyme is composed of one of each subunit. The enzyme utilized either glutamine ( K , 0.15 mM) or NH3 (K, 17 mM) and requires free Mg2+ for maximal activity with the optimal level between 4 mM and 10 mM. Hill plots of MgATP saturation data yielded coefficients of 1.2 and 1.4 at pH 8.0 and 8.5, respectively. A Hill equation was derived on the assumptions that MgATP binds at the same time to two distinct sub-sites as was shown to be the case for carbamoylphosphate synthetase from Escherichia coli and that these sub-sites are strictly non-interacting. The resulting theoretical Hill coefficients correspond very closely to the experimental coefficients. Carbamoylphosphate synthetase activity was subject to activation by ornithine and N-acetylornithine and feedback inhibition by UMP. Carbamoylphosphate synthetase from P. aerugino.ra does not associate under all conditions examined, establishing that self-association does not play a role in regulation of enzyme activity as suggested by other workers for the enzyme from E. coli.Carbamoylphosphate is an intermediate in the biosynthesis of arginine and pyrimidines. In enteric bacteria [l -51 it is synthesized by a single enzyme, carbamoylphosphate synthetase, which catalyzes the following reaction :Ammonia can replace glutamine as a nitrogen donor in the reaction but the affinity for ammonia is much less than that for glutamine; the latter substrate is considered the physiological nitrogen donor. The enteric enzymes [l -51 are all subject to cumulative repression by arginine and a pyrimidine compound and to feedback control: U M P inhibits activity and ornithine stimulates it. The combined effects provide an efficient mechanism for controlling the supply of carbamoylphosphate for arginine and pyrimidine biosynthesis.Examination of carbamoylphosphate metabolism in Pseudomonas aeruginosa is of particular interest in view of the significant differences that distinguish arginine metabolism in this organism from that in enteric bacteria [6,7]. These differences include the ability of P. ueruginosu and other fluorescent pseudomonads to degrade arginine via the arginine deiminase pathway (Fig. 1). This pathway involves the activity of carbamate kinase which catalyzes the phosphorylation of ADP by carbamoylphosphate [7] according to the following reaction :The possible presence of two enzyme...

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“…Expression of this enzyme can be repressed up to 18-fold by the presence of exogenous arginine (13,20,40). The second enzyme, succinylornithineaminotransferase (SOAT; encoded by argD), is able to catalyze three distinct transaminase reactions within the arginine metabolic network: (i) the aforementioned OAT reaction, (ii) the biosynthesis of acetylornithine (ACOAT), and (iii) the transamination of succinylornithine (SOAT), from which the enzyme gets its name (Fig.…”

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confidence: 99%

Regulation of ornithine utilization in Pseudomonas aeruginosa (PAO1) is mediated by a transcriptional regulator, OruR

Hebert

Houghton

1997

J Bacteriol

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We have used transpositional mutagenesis of a proline auxotroph (PAO951) to isolate an ornithine utilization (oru) mutant of Pseudomonas aeruginosa (PAO951-4) that was unable to use ornithine efficiently as the sole carbon and nitrogen source. DNA sequence analysis of the inactivated locus confirmed that the transposon had inserted into a locus whose product demonstrated significant primary sequence homology to members of the AraC family of transcriptional activators. DNA mobility shift assays affirmed this potential regulatory function and indicated that the inactivated gene encodes a transcriptional regulator, which has been designated OruR. In trying to define the ornithine utilization phenotype further, a similar inactivation was engineered in the wild-type strain, PAO1. The resulting isolate (PAO1R4) was totally unable to use ornithine as the sole carbon source. Despite the intensified phenotype, this isolate failed to demonstrate significant changes in any of the catabolic or anabolic enzymes that are known to be subject to regulation by the presence of either ornithine or arginine. It did, however, show modified levels of an enzyme, ornithine acetyltransferase (OAcT), that was previously thought to have merely an anaplerotic activity. Definition of this oruR locus and its effects upon OAcT activity provide evidence that control of ornithine levels in P. aeruginosa may have a significant impact upon how the cell is able to monitor and regulate the use of arginine and glutamate as sources of either carbon or nitrogen.The versatility with which Pseudomonas aeruginosa PAO1 is able to utilize a wide variety of compounds as sole carbon and nitrogen sources is manifest in the complex and intricate nature of its arginine metabolism (4, 11) (Fig. 1). Unlike the situation in enteric bacteria, where the entire arginine biosynthetic regulon is controlled by a single arginine repressor (9), only two of the genes that specifically relate to arginine biosynthesis in P. aeruginosa, namely, argF and argD, have been shown to be regulated by arginine (4,11,27). Significantly, perhaps, both these genes encode enzymes (anabolic ornithine transcarbamylase [aOTCase] [argF] and ornithine aminotransferase [OAT] [argD]) that catalyze important branch points in arginine metabolism (Fig.

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Regulation of Enzyme Synthesis in the Arginine Biosynthetic Pathway of Pseudomonas aeruginosa

Cited by 26 publications

References 20 publications

Transcriptome Analysis of the ArgR Regulon inPseudomonas aeruginosa

Transcriptome Analysis of the ArgR Regulon inPseudomonas aeruginosa

Carbamoylphosphate Synthetase from Pseudomonas aeruginosa

Regulation of ornithine utilization in Pseudomonas aeruginosa (PAO1) is mediated by a transcriptional regulator, OruR

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