Adjustment of polyamine contents in Escherichia coli

Kashiwagi, Keiko; Igarashi, Kazuei

doi:10.1128/jb.170.7.3131-3135.1988

Cited by 47 publications

(34 citation statements)

References 25 publications

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“…The existence of membrane protein CadB helps solve this basic problem. Although the excretion of polyamines has previously been studied with respect to K+ and osmolarity (40) and polyamine transport systems have been investigated elsewhere (29,30,39), the relation of these studies to the pH response has not been thoroughly considered. An ability of CadB not only to facilitate the excretion of cadaverine but to act in such a way as to coordinate cadaverine excretion with lysine uptake makes an attractive model.…”

Section: Discussionmentioning

confidence: 99%

Nucleotide sequence of the Escherichia coli cad operon: a system for neutralization of low extracellular pH

1992

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Lysine decarboxylase ofEscherichia coli has been the subject of enzymological studies, and the gene encoding lysine decarboxylase (cadA4) and a regulatory gene (cadR) have been mapped. This enzyme is induced at low pH in the presence of lysine and achieves maximal level under anaerobic conditions. The induction of lysine decarboxylase increases the pH of the extracellular medium and provides a distinctive marker in tests of clinical strains. We report the sequence of the cad operon encoding lysine decarboxylase, a protein of 715 amino acids, and another protein, CadB, of 444 amino acids. The amino acid sequence of lysine decarboxylase showed high homology to that of the lysine decarboxylase of Hafnia alvei with less homology to the sequence of speC, which encodes the biosynthetic ornithine decarboxylase of E. coli. The cadA and cadB genes were separately cloned and placed under the control of lac and tac promoters, respectively, to facilitate independent study of their physiological effects. The cadB gene product had a mobility characteristic of a smaller protein on protein gels, analogous to that found for some other membrane proteins. The CadB sequence showed homology to that of ArcD of Pseudomonas aeruginosa, encoding an arginine/ornithine antiporter. Excretion studies of various strains, the coinduction of cadB and cadA, and the attractive physiological role for an antiport system led to a model for the coupled action of cadA and cadB in uptake of lysine, the reduction of H+ concentration, and excretion of cadaverine.Two types of amino acid decarboxylases exist in Escherichia coli. Biosynthetic enzymes are involved in the synthesis of polyamines and are expressed at low levels regardless of pH variation (56). Biodegradative enzymes such as lysine decarboxylase are strongly induced at acidic pH (5,49,56) and hence have a possible role in maintaining pH homeostasis or extending the growth period by detoxification of the extracellular medium (20). Although it has been stated elsewhere that the cadaverine generated from decarboxylation of L-lysine is not further metabolized for energy production but is excreted out of the cell as part of a countermeasure to acidic environment (49), no direct detailed analysis of this aspect has been reported. Unlike arginine and ornithine decarboxylases, two types of enzymes that have been well characterized previously (56), only the inducible form of lysine decarboxylase has been analyzed previously (49, 50), although some evidence has indicated the presence of a pH-constitutive form of lysine decarboxylase in E. coli (24,64).Mutants of cadA have been isolated, and the gene was first mapped to around 92 min on the E. coli genome (57). Subsequent detailed mapping of in vivo Mu dX operon fusion strains deficient in lysine decarboxylase activity and mini-Mu clones revealed that cadA4 was at 93.7 min (5). In studies of protein expression from the plasmid pLC4-5, it was found that cadA4 and lysU were both expressed (59); however, the orientation and order relative to the surrounding...

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Section: Discussionmentioning

confidence: 99%

Nucleotide sequence of the Escherichia coli cad operon: a system for neutralization of low extracellular pH

1992

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“…The overexpression of full-length ADC in the double mutant raises the spermidine concentration above the level observed in the speA ϩ speC ϩ strain, likely triggering its down-regulation via SAT or S-adenosylmethionine decarboxylase along with the excretion of putrescine via PotE (30), lowering putrescine levels. Thus, the complementation of the double mutant with speA is sufficient for recovery of the biofilm phenotype: however, the toxic effects of high polyamine levels are likely triggering its downregulation (30).…”

Section: Discussionmentioning

confidence: 99%

Polyamines Are Essential for the Formation of Plague Biofilm

Patel¹,

Wortham²,

et al. 2006

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We provide the first evidence for a link between polyamines and biofilm levels in Yersinia pestis, the causative agent of plague. Polyamine-deficient mutants of Y. pestis were generated with a single deletion in speA or speC and a double deletion mutant. The genes speA and speC code for the biosynthetic enzymes arginine decarboxylase and ornithine decarboxylase, respectively. The level of the polyamine putrescine compared to the parental speA ؉ speC ؉ strain (KIM6؉) was depleted progressively, with the highest levels found in the Y. pestis ⌬speC mutant (55% reduction), followed by the ⌬speA mutant (95% reduction) and the ⌬speA ⌬speC mutant (>99% reduction). Spermidine, on the other hand, remained constant in the single mutants but was undetected in the double mutant. The growth rates of mutants with single deletions were not altered, while the ⌬speA ⌬speC mutant grew at 65% of the exponential growth rate of the speA ؉ speC ؉ strain. Biofilm levels were assayed by three independent measures: Congo red binding, crystal violet staining, and confocal laser scanning microscopy. The level of biofilm correlated to the level of putrescine as measured by high-performance liquid chromatography-mass spectrometry and as observed in a chemical complementation curve. Complementation of the ⌬speA ⌬speC mutant with speA showed nearly full recovery of biofilm to levels observed in the speA ؉ speC ؉ strain. Chemical complementation of the double mutant and recovery of the biofilm defect were only observed with the polyamine putrescine.

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“…It has been argued that feedback inhibition controls putrescine synthesis (46), and the opposite has also been argued (5). It has been proposed that putrescine export controls intracellular putrescine (13,16), but putrescine is not excreted in certain media (45). Putrescine catabolism has not been considered as a possible homeostatic control mechanism, but only because polyamine catabolism has not been extensively studied.…”

Section: Discussionmentioning

confidence: 99%

The Escherichia coli gabDTPC Operon: Specific γ-Aminobutyrate Catabolism and Nonspecific Induction

et al. 2002

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Nitrogen limitation induces the nitrogen-regulated (Ntr) response, which includes proteins that assimilate ammonia and scavenge nitrogen. Nitrogen limitation also induces catabolic pathways that degrade four metabolically related compounds: putrescine, arginine, ornithine, and ␥-aminobutyrate (GABA). We analyzed the structure, function, and regulation of the gab operon, whose products degrade GABA, a proposed intermediate in putrescine catabolism. We showed that the gabDTPC gene cluster constitutes an operon based partially on coregulation of GabT and GabD activities and the polarity of an insertion in gabT on gabC. A ⌬gabDT mutant grew normally on all of the nitrogen sources tested except GABA. The unexpected growth with putrescine resulted from specific induction of gab-independent enzymes. Nac was required for gab transcription in vivo and in vitro. Ntr induction did not require GABA, but various nitrogen sources did not induce enzyme activity equally. A gabC (formerly ygaE) mutant grew faster with GABA and had elevated levels of gab operon products, which suggests that GabC is a repressor. GabC is proposed to reduce nitrogen source-specific modulation of expression. Unlike a wild-type strain, a gabC mutant utilized GABA as a carbon source and such growth required S . Previous studies showing S -dependent gab expression in stationary phase involved gabC mutants, which suggests that such expression does not occur in wild-type strains. The seemingly narrow catabolic function of the gab operon is contrasted with the nonspecific (nitrogen source-independent) induction. We propose that the gab operon and the Ntr response itself contribute to putrescine and polyamine homeostasis.

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Adjustment of polyamine contents in Escherichia coli

Cited by 47 publications

References 25 publications

Nucleotide sequence of the Escherichia coli cad operon: a system for neutralization of low extracellular pH

Nucleotide sequence of the Escherichia coli cad operon: a system for neutralization of low extracellular pH

Polyamines Are Essential for the Formation of Plague Biofilm

The Escherichia coli gabDTPC Operon: Specific γ-Aminobutyrate Catabolism and Nonspecific Induction

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