Secretion of d-alanine by Escherichia coli

Katsube, Satoshi; Sato, Kenzo; Ando, Tasuke; Isogai, Emiko; Yoneyama, Hiroshi

doi:10.1099/mic.0.000305

Cited by 12 publications

(17 citation statements)

References 33 publications

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“…The third possibility is very unlikely because, as described previously, both strains are isogenic. With regard to the last possibility, E. coli has recently been found to possess a system(s) that secretes D-alanine [30], an observation that correlates well with the lower alanine level in MG1655∆ alaE ∆ dadA as compared to that in MLA301∆ alaE (Figure 1b).…”

Section: Resultsmentioning

confidence: 85%

L-Alanine Exporter, AlaE, of Escherichia coli Functions as a Safety Valve to Enhance Survival under Feast Conditions

Katsube¹,

Ando²,

Yoneyama³

2019

IJMS

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The intracellular level of amino acids is determined by the balance between their anabolic and catabolic pathways. L-alanine is anabolized by three L-alanine synthesizing enzymes and catabolized by two racemases and D-amino acid dehydrogenase (DadA). In addition, its level is regulated by L-alanine movement across the inner membrane. We identified the novel gene alaE, encoding an L-alanine exporter. To elucidate the physiological function of L-Alanine exporter, AlaE, we determined the susceptibility of alaE-, dadA-, and alaE/dadA-deficient mutants, derived from the wild-type strain MG1655, to L-alanyl-L-alanine (Ala-Ala), which shows toxicity to the L-alanine-nonmetabolizing variant lacking alaE. The dadA-deficient mutant has a similar minimum inhibitory concentration (MIC) (>1.25 mg/mL) to that observed in MG1655. However, alaE- and alaE/dadA-deficient mutants had MICs of 0.04 and 0.0025 mg/mL, respectively. The results suggested that the efficacy of AlaE to relieve stress caused by toxic intracellular accumulation of L-alanine was higher than that of DadA. Consistent with this, the intracellular level of alanine in the alaE-mutant was much higher than that in MG1655 and the dadA-mutant. We, therefore, conclude that AlaE functions as a ‘safety-valve’ to prevent the toxic level accumulation of intracellular L-alanine under a peptide-rich environment, such as within the animal intestine.

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Section: Resultsmentioning

confidence: 85%

L-Alanine Exporter, AlaE, of Escherichia coli Functions as a Safety Valve to Enhance Survival under Feast Conditions

Katsube¹,

Ando²,

Yoneyama³

2019

IJMS

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“…The two enantiomers of dl -alanine were completely separated using the same chiral stationary phase [ 47 ]. Alanine, also, one of the essential building blocks in the biosynthesis of proteins, where the l -form of alanine was found to be one of the essential amino acids in the human genetic code [ 47 ], while the d -form exists in bacterial cell walls [ 129 ].…”

Section: Swcnts and Mwcnts For Chiral Separation In Biological Actmentioning

confidence: 99%

Application of Carbon Nanotubes in Chiral and Achiral Separations of Pharmaceuticals, Biologics and Chemicals

et al. 2017

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Carbon nanotubes (CNTs) possess unique mechanical, physical, electrical and absorbability properties coupled with their nanometer dimensional scale that renders them extremely valuable for applications in many fields including nanotechnology and chromatographic separation. The aim of this review is to provide an updated overview about the applications of CNTs in chiral and achiral separations of pharmaceuticals, biologics and chemicals. Chiral single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) have been directly applied for the enantioseparation of pharmaceuticals and biologicals by using them as stationary or pseudostationary phases in chromatographic separation techniques such as high-performance liquid chromatography (HPLC), capillary electrophoresis (CE) and gas chromatography (GC). Achiral MWCNTs have been used for achiral separations as efficient sorbent objects in solid-phase extraction techniques of biochemicals and drugs. Achiral SWCNTs have been applied in achiral separation of biological samples. Achiral SWCNTs and MWCNTs have been also successfully used to separate achiral mixtures of pharmaceuticals and chemicals. Collectively, functionalized CNTs have been indirectly applied in separation science by enhancing the enantioseparation of different chiral selectors whereas non-functionalized CNTs have shown efficient capabilities for chiral separations by using techniques such as encapsulation or immobilization in polymer monolithic columns.

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“…Nevertheless, it is only used on a small‐scale because of its high input requirements and low enantiomeric excess (e.e.) value . Enzyme immobilization has been recently applied to produce D‐Ala because this method is highly stable and reliable.…”

Section: Introductionmentioning

confidence: 99%

“…value. [9][10][11] Enzyme immobilization has been recently applied to produce D-Ala because this method is highly stable and reliable. Co-immobilized enzymes have been used to prepare optically pure D-Ala from sodium pyruvate.…”

Section: Introductionmentioning

confidence: 99%

Kinetic resolution of N‐acetyl‐DL‐alanine methyl ester using immobilized Escherichia coli cells bearing recombinant esterase from Bacillus cereus

et al. 2018

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D-alanine is widely used in medicine, food, additives, cosmetics, and other consumer items. Esterase derived from Bacillus cereus WZZ001 exhibits high hydrolytic activity and stereoselectivity. In this study, we expressed the esterase gene in Escherichia coli BL21 (DE3). We analyzed the biocatalytic resolution of N-acetyl-DL-alanine methyl ester by immobilized whole E. coli BL21 (DE3) cells, which were prepared through embedding and cross-linking. We analyzed biocatalytic resolution under the optimal conditions of pH of 7.0, temperature of 40°C and substrate concentration of at 700 mM with an enantiomeric excess of 99.99% and e.e. of 99.50%. The immobilized recombinant B. cereus esterase E. coli BL21 (DE3) cells exhibited excellent reusability and retained 86.04% of their initial activity after 15 cycles of repeated reactions. The immobilized cells are efficient and stable biocatalysts for the preparation of N-acetyl-D-alanine methyl esters.

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Secretion of d-alanine by Escherichia coli

Cited by 12 publications

References 33 publications

L-Alanine Exporter, AlaE, of Escherichia coli Functions as a Safety Valve to Enhance Survival under Feast Conditions

L-Alanine Exporter, AlaE, of Escherichia coli Functions as a Safety Valve to Enhance Survival under Feast Conditions

Application of Carbon Nanotubes in Chiral and Achiral Separations of Pharmaceuticals, Biologics and Chemicals

Kinetic resolution of N‐acetyl‐DL‐alanine methyl ester using immobilized Escherichia coli cells bearing recombinant esterase from Bacillus cereus

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