Hidden overflow pathway to L-phenylalanine in Pseudomonas aeruginosa

Fiske, Michael J.; Whitaker, Robert J.; Jensen, Roy A.

doi:10.1128/jb.154.2.623-631.1983

Cited by 37 publications

(11 citation statements)

References 31 publications

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“…uses it as substrate. Essentially the same phenomenon occurs in P. aeruginosa when chorismate accumulation is greatly increased following early-pathway deregulation (17). In this case, cytoplasmic chorismate, largely unaccepted by the feedback-sensitive prephenate dehydratase and cyclohexadienyl dehydrogenase enzymes in the cytoplasm, is apparently forced to the periplasm where periplasmic CM-F and cyclohexadienyl dehydratase participate in the overall conversion to large quantities of phenylalanine.…”

Section: Discussionmentioning

confidence: 89%

The aroQ-encoded monofunctional chorismate mutase (CM-F) protein is a periplasmic enzyme in Erwinia herbicola

et al. 1993

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Enteric bacteria possess two species of chorismate mutase which exist as catalytic domains on the amino termini of the bifunctional PheA and TyrA proteins. In addition, some of these organisms possess a third chorismate mutase, CM-F, which exists as a small monofunctional protein. The CM-F gene (denoted aroQ) from Erwinia herbicola was cloned and sequenced for the first time. A strategy for selection by functional complementation in a chorismate mutase-free Escherichia coli background was devised by using a recombinant plasmid derivative of pUC18 carrying a Zymomonas mobilis tyrC insert which encodes cyclohexadienyl dehydrogenase. The aroQ gene is 543 bp in length, predicting a 181-residue protein product having a calculated molecular mass of 20,299 Da. The E. herbicola aroQ promoter is recognized by E. coli, and a putative sigma-70 promoter region was identified. N-terminal amino acid sequencing of the purified CM-F protein indicated cleavage of a 20-residue signal peptide. This was consistent with the monomeric molecular mass determined for the enzyme of about 18,000 Da. The native enzyme is a homodimer. The implied translocation of CM-F was confirmed by osmotic shock experiments which demonstrated a periplasmic location. Immunogold electron microscopy indicated a polar localization within the periplasm. Polyclonal antibody raised against E. herbicola CM-F did not cross-react with the CM-F protein from the closely related Serratia rubidaea, as well as from a number of other gram-negative bacteria. Furthermore, when the E. herbicola aroQ gene was used as a probe in Southern blot hybridizations with EcroRI digests of chromosomal DNA from S. rubidaea and other enteric organisms, no hybridization was detected at low stringency. Thus, the aroQ gene appears to be unusually divergent among closely related organisms. The deduced CM-F amino acid sequence did not exhibit compelling evidence for homology with the monofunctional chorismate mutase protein of Bacillus subtilis.

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Section: Discussionmentioning

confidence: 89%

The aroQ-encoded monofunctional chorismate mutase (CM-F) protein is a periplasmic enzyme in Erwinia herbicola

et al. 1993

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“…The growth advantage with phenylalanine displayed by lasR mutants could be at the level of transport or degradation. In either case, the antimetabolite fluorophenylalanine, a phenylalanine analogue that has long been used to study amino acid metabolism in P. aeruginosa (Fiske et al ., 1983), would be predicted to differentially affect the growth of lasR mutants. Indeed, this was the case.…”

Section: Resultsmentioning

confidence: 99%

Growth phenotypes of Pseudomonas aeruginosa lasR mutants adapted to the airways of cystic fibrosis patients

D’Argenio

Hoffman

et al. 2007

Molecular Microbiology

324

364

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SummaryThe opportunistic pathogen Pseudomonas aeruginosa undergoes genetic change during chronic airway infection of cystic fibrosis (CF) patients. One common change is a mutation inactivating lasR, which encodes a transcriptional regulator that responds to a homoserine lactone signal to activate expression of acute virulence factors. Colonies of lasR mutants visibly accumulated the iridescent intercellular signal 4-hydroxy-2-heptylquinoline. Using this colony phenotype, we identified P. aeruginosa lasR mutants that emerged in the airway of a CF patient early during chronic infection, and during growth in the laboratory on a rich medium. The lasR loss-of-function mutations in these strains conferred a growth advantage with particular carbon and nitrogen sources, including amino acids, in part due to increased expression of the catabolic pathway regulator CbrB. This growth phenotype could contribute to selection of lasR mutants both on rich medium and within the CF airway, supporting a key role for bacterial metabolic adaptation during chronic infection. Inactivation of lasR also resulted in increased b-lactamase activity that increased tolerance to ceftazidime, a widely used b-lactam antibiotic. Loss of LasR function may represent a marker of an early stage in chronic infection of the CF airway with clinical implications for antibiotic resistance and disease progression.

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“…The periplasmic location of AroQ has been demonstrated (10) with data similar to that shown by Xia et al for Erwinia herbicola (28), and the presence of a periplasmic species of aromatic aminotransferase has also been demonstrated (10). This suite of enzymes in the spatial location of the periplasm constitutes the "hidden overflow pathway to L-phenylalanine" reported in 1983 (9). A given AGN molecule in the periplasm could be transformed to Lphenylalanine by PheC or to prephenate via periplasmic aminotransferase.…”

Section: Discussionmentioning

confidence: 96%

L-Arogenate Is a Chemoattractant Which Can Be Utilized as the Sole Source of Carbon and Nitrogen by Pseudomonas aeruginosa

Fischer¹,

Jiang²,

Gu³

et al. 1997

Appl Environ Microbiol

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L-Arogenate is a commonplace amino acid in nature in consideration of its role as a ubiquitous precursor of L-phenylalanine and/or L-tyrosine. However, the questions of whether it serves as a chemoattractant molecule and whether it can serve as a substrate for catabolism have never been studied. We found that Pseudomonas aeruginosa recognizes L-arogenate as a chemoattractant molecule which can be utilized as a source of both carbon and nitrogen. Mutants lacking expression of either cyclohexadienyl dehydratase or phenylalanine hydroxylase exhibited highly reduced growth rates when utilizing L-arogenate as a nitrogen source. Utilization of L-arogenate as a source of either carbon or nitrogen was dependent upon 54 , as revealed by the use of an rpoN null mutant. The evidence suggests that catabolism of L-arogenate proceeds via alternative pathways which converge at 4-hydroxyphenylpyruvate. In one pathway, prephenate formed in the periplasm by deamination of L-arogenate is converted to 4-hydroxyphenylpyruvate by cyclohexadienyl dehydrogenase. The second route depends upon the sequential action of periplasmic cyclohexadienyl dehydratase, phenylalanine hydroxylase, and aromatic aminotransferase.

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Hidden overflow pathway to L-phenylalanine in Pseudomonas aeruginosa

Cited by 37 publications

References 31 publications

The aroQ-encoded monofunctional chorismate mutase (CM-F) protein is a periplasmic enzyme in Erwinia herbicola

The aroQ-encoded monofunctional chorismate mutase (CM-F) protein is a periplasmic enzyme in Erwinia herbicola

Growth phenotypes of Pseudomonas aeruginosa lasR mutants adapted to the airways of cystic fibrosis patients

L-Arogenate Is a Chemoattractant Which Can Be Utilized as the Sole Source of Carbon and Nitrogen by Pseudomonas aeruginosa

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