Lysine secretion by wild-type Corynebacterium glutamicum triggered by dipeptide uptake

Erdmann, Andreas; Weil, Brita; Krämer, Reinhard

doi:10.1099/00221287-139-12-3115

Cited by 34 publications

(43 citation statements)

References 30 publications

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“…Dipeptides provide a means to increase the intracellular level of an amino acid, as their entry into the cytoplasm occurs via the peptide uptake systems. The Lys-Ala dipeptide has previously been employed as a means to increase the intracellular levels of Lys in C. glutamicum (31). We found that the ybjE mutant was impaired for growth in MA medium containing Lys-Ala but not in MA medium containing Arg-Ala or the histidinylalanine (His-Ala) dipeptides (Fig.…”

Section: Resultsmentioning

confidence: 66%

“…5), fulfill the genetic criteria expected if its product were to mediate export of Lys. Lys excretion in C. glutamicum is thought to represent an example of limited catabolism as a physiological model that has been proposed to explain the biological need for amino acid export, since Lys export is required during growth in a medium containing lysyl-dipeptides, as C. glutamicum does not have the capacity to catabolize Lys (14,31). Besides export, another way to redress the growth inhibition caused by elevated cytoplasmic content of an amino acid could be via the activation of its corresponding catabolic route.…”

Section: Discussionmentioning

confidence: 99%

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Distinct Paths for Basic Amino Acid Export in Escherichia coli: YbjE (LysO) Mediates Export of l -Lysine

Pathania

Sardesai

2015

J Bacteriol

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In Escherichia coli, argO encodes an exporter for L-arginine (Arg) and its toxic analogue canavanine (CAN), and its transcriptional activation and repression, by Arg and L-lysine (Lys), respectively, are mediated by the regulator ArgP. Accordingly argO and argP mutants are CAN supersensitive (CAN ss IMPORTANCEThis work ascribes a lysine export function to the product of the ybjE gene of Escherichia coli, leading to a physiological scenario wherein two proteins, ArgO and YbjE, perform the task of separately exporting arginine and lysine, respectively, which is distinct from that seen for Corynebacterium glutamicum, where the ortholog of ArgO, LysE, mediates export of both arginine and lysine. Repression of argO transcription by lysine is thought to effect this separation. Accordingly, ArgO mediates lysine export when repression of its transcription by lysine is bypassed. Repression of ybjE transcription by arginine via the ArgR repressor, together with the lysine repression of argO effected by ArgP, is indicative of a mechanism of maintenance of arginine/lysine balance in E. coli. Bacteria possess membrane exporters for a variety of compounds. Their activities to a large extent are thought to play an adaptive role in mitigating the detrimental effects on bacterial growth caused by the presence of biotic stresses, such as those imposed by antibiotics, heavy metals, and other toxic compounds, in their natural environments. While it is easy to come to terms with the existence of proteins that mediate export of compounds described above, the presence of specific export systems for cellular metabolites such as sugars and amino acids appears somewhat enigmatic. For example, Escherichia coli encodes multiple proteins for the export of sugars, such as glucose and lactose (1), and for arabinose (2, 3). In addition, the occurrence of proteins mediating export of amino acids, such as alanine (4), arginine (5), aromatic amino acids (6), cysteine (7, 8), leucine (9), threonine (10, 11) and valine (12), in E. coli has been reported. While the physiological basis for the existence of amino acid exporters is not clear, their occurrence is relatively widespread in bacteria (13,14). It is thought that an amino acid exporter may serve to contribute to the fitness of an organism during conditions of metabolic imbalance resulting from excessive levels of its amino acid substrate in the cytoplasm (13,14). An alternative view could be that export of the amino acid occurs by chance, with the cognate substrate being a naturally occurring structurally related antimetabolite present in the environment. As an example of the latter, one mechanism contributing to the resistance of E. coli to the plant-derived antimetabolite canavanine (CAN), an L-arginine analogue, involves its export by ArgO, the ortholog of the basic amino acid exporter LysE of Corynebacterium glutamicum, following its uptake (5). Harnessing the amino acid export potential of a given bacterium has found widespread application in the commercial production of amin...

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Section: Resultsmentioning

confidence: 66%

Section: Discussionmentioning

confidence: 99%

Distinct Paths for Basic Amino Acid Export in Escherichia coli: YbjE (LysO) Mediates Export of l -Lysine

Pathania

Sardesai

2015

J Bacteriol

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“…The uptake of lysine-containing dipeptides by C. glutamicum has been recently studied (10). Similar to Streptococcus cremoris (12,21), uptake of various lysine-and glutamate-containing dipeptides was found to be driven by the membrane potential, according to a secondary mechanism.…”

Section: Resultsmentioning

confidence: 99%

“…In the case of lysine, a detailed kinetic mechanism for excretion involving a secondary process has been described (4). On the one hand, isoleucine, like lysine, is not metabolized in C. glutamicum and has thus to be excreted under conditions of growth on peptides (4,10). On the other hand, isoleucine clearly differs from lysine with respect to hydrophobicity and thus to the ability to cross the membrane by diffusion.…”

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confidence: 99%

Quantitative discrimination of carrier-mediated excretion of isoleucine from uptake and diffusion in Corynebacterium glutamicum

Zittrich

Krämer

1994

J Bacteriol

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The efflux of isoleucine in whole cells of Corynebacterium glutamicum was studied. The different amino acid fluxes across the plasma membrane were functionally discriminated into passive diffusion, carrier-mediated excretion, and carrier-mediated uptake. Detailed kinetic analysis was made possible by controlled variation of internal isoleucine from low concentrations to 100 mM by feeding with mixtures of isoleucine-containing peptides. Isoleucine diffusion was experimentally separated and proceeded with a first-order rate constant of 0.083 min-1 or 0.13 microliters.min-1.mg (dry mass)-1, which corresponds to a permeability of 2 x 10(-8) cm.s-1. Uptake of isoleucine was constant at a rate of 1.1 nmol.min-1.mg (dry mass)-1. Carrier-mediated isoleucine excretion was zero below a threshold of 8 mM cytosolic isoleucine. Above this level, a Michaelis-Menten-type kinetics was observed, with a Km of 21 mM (13 mM plus 8 mM threshold value) and a Vmax of 14.5 nmol.min-1.mg (dry mass)-1. The activity of the isoleucine excretion carrier depended on the presence of a membrane potential. Excretion was specific for L-isoleucine (and presumably L-leucine) and could be inhibited by SH reagents.

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“…Instead, specific efflux systems are known in detail for the removal of fermentation products (1) or the removal of heavy metal ions (21), or they are present to expel antibiotics (25) and are thus directly required for the survival or metabolism of the cell. However, as recently shown, C. glutamicum can take up peptides, which become hydrolyzed to their amino acid constituents within the cell (12). As a consequence, the organism then has to deal with the surplus amino acids which cannot be metabolized and remove them in this particular situation.…”

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confidence: 99%

Unbalance of L-lysine flux in Corynebacterium glutamicum and its use for the isolation of excretion-defective mutants

et al. 1995

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We found that the simple addition of L-methionine to the wild type of Corynebacterium glutamicum results in excretion of the cellular building block L-lysine up to rates of 2.5 nmol/min/mg (dry weight). Biochemical analyses revealed that L-methionine represses the homoserine dehydrogenase activity and reduces the intracellular L-threonine level from 7 to less than 2 mM. Since L-lysine synthesis is regulated mainly by L-threonine (plus L-lysine) availability, the result is enhanced flux towards L-lysine. This indicates a delicate and not well controlled type of flux control at the branch point of aspartate semialdehyde conversion to either L-lysine or L-threonine, probably due to the absence of isoenzymes in C. glutamicum. The inducible system of L-lysine excretion discovered was used to isolate mutants defective in the excretion of this amino acid. One such mutant characterized in detail accumulated 174 mM L-lysine in its cytosol without extracellular excretion of L-lysine, whereas the wild type accumulated 53 mM L-lysine in the cytosol and 5.9 mM L-lysine in the medium. The mutant was unaffected in L-lysine uptake or L-isoleucine or L-glutamate excretion, and also the membrane potential was unaltered. This mutant therefore represents a strain with a defect in an excretion system for the primary metabolite L-lysine.

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Lysine secretion by wild-type Corynebacterium glutamicum triggered by dipeptide uptake

Cited by 34 publications

References 30 publications

Distinct Paths for Basic Amino Acid Export in Escherichia coli: YbjE (LysO) Mediates Export of l -Lysine

Distinct Paths for Basic Amino Acid Export in Escherichia coli: YbjE (LysO) Mediates Export of l -Lysine

Quantitative discrimination of carrier-mediated excretion of isoleucine from uptake and diffusion in Corynebacterium glutamicum

Unbalance of L-lysine flux in Corynebacterium glutamicum and its use for the isolation of excretion-defective mutants

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