Lysine uptake and exchange in Corynebacterium glutamicum

Bröer, Stefan; Krämer, Reinhard

doi:10.1128/jb.172.12.7241-7248.1990

Cited by 43 publications

(19 citation statements)

References 24 publications

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“…mg dry cells-'. The latter value was in good agreement with the maximum uptake rate as determined in the wild-type strain [29].…”

Section: Lpitie Is Riot Excreted By Its Uptcike Systetn: Testing Modesupporting

confidence: 87%

“…(c) Lysine excretion is not due to functional inversion of the lysine uptake system (model 111). We recently showed [29] that the observed uptake of labelled lysine is catalyzed by a homologous antiport mechanism, a process which obviously is not able to mediate lysine export. Wecould also demonstrate heterologous antiport against alanine, valine or isoleucine in lysine-auxotrophic strains, yet this mechanism is also not able to mediate lysine export.…”

Section: Discussionmentioning

confidence: 99%

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Lysine excretion by Corynebacterium glutamicum

Bröer

Krämer

1991

European Journal of Biochemistry

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Corynehacterium glutamicum effectively excretes lysine when the internal lysine concentration is elevated. Lysine efflux was investigated using selected mutants which are not able to regulate lysine biosynthesis by feedback inhibition. Secretion of lysine is not the consequence of unspecific permeability of the plasma membrane but is mediated by a secretion carrier which is specific for lysine. Lysine export is characterized by high activation energy and follows Michaelis-Menten type kinetics with an internal K , of 20 mM and a VmaX of 12 nmol . min-' . mg dry cells-Excretion can proceed against a preexisting chemical gradient and against the electrical potential, which rules out a previously suggested pore model. Lysine excretion can also be observed in the wild-type strain especially under conditions of peptide uptake. Its possible physiological function may be related to regulation of internal amino acid concentrations under special growth conditions. Solute excretion in bacteria, although a widespread phenomenon, is poorly understood. There are only few systems which are reasonably well described. Various mechanisms have been postulated for the excretion of amino acids in C. glutamicum. (a) It is still widely accepted that excretion of these solutes may occur as a result of a physically changed (leaky) membrane [18, 191 (leak model Excretion of lysine is difficult to detect in the wild-type strain C. glutamicunz ATCC 13032. In strains where aspartate kinase, the key enzyme in the regulation of lysine biosynthesis,

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“…mg dry cells-'. The latter value was in good agreement with the maximum uptake rate as determined in the wild-type strain [29].…”

Section: Lpitie Is Riot Excreted By Its Uptcike Systetn: Testing Modesupporting

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Lysine excretion by Corynebacterium glutamicum

Bröer

Krämer

1991

European Journal of Biochemistry

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“…Determination of cytoplasmic volume is based on comparison of the space occupied by a permeable (water) and an impermeable marker (taurine). The procedure is described in detail elsewhere (Broer & Kramer, 1990). Measurement of cells grown in complex media resulted in a value of 1.8 pl (mg dry wt)-l. The distribution of the lipophilic cation [U-'4C]tetraphenylphosphonium was measured to determine the membrane potential.…”

Section: Methodsmentioning

confidence: 99%

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

Erdmann

Weil

Krämer

1993

Journal of General Microbiology

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In Cuvynebactevium glutamicum peptide uptake increases the internal concentration of amino acids and thus triggers amino acid secretion. The peptide uptake system is stimulated by a factor of two in cells grown on pure peptone medium in comparison to peptone media with additional carbon sources. Uptake depends on the protonmotive force and shows a broad substrate spectrum. Peptide uptake is characterized by a K,,, of about 230 PM and a Ymax of 12 nmol min-' (mg dry wt)-' for the peptide lysyl-alanine (Lys-Ala). Lysine secretion in the wild-type of C. glutarnicum does not show Michaelis-Menten-type kinetics as reported for the producing strains DG 52-5 and MH 20-22B. The secretion of lysine depends on the composition of the medium in which the cells were grown prior to the initiation of secretion by peptide uptake. The lack of secretion activity when the cells are shifted to peptone medium in the presence of chloramphenicol indicates that protein synthesis is necessary for this regulatory process.

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“…Both forces thus work together which allows a high rate of exchange. The Ap or one of its components can affect the translocation process through (de)protonation of the substrate(s) and/or through the differential charge of the individual substrates, e.g., sugar-phosphate/phosphate [87], malate/lactate [43], oxalate/ formate [82], and lysine/alanine exchange [88]. Some systems catalyze precursor/product exchange or solute-H + symport, depending on the concentrations of the solutes and protons on either side of the membrane, the dissociation constants (K o) for these molecules and the magnitude of the membrane potential, e.g., lactose/galactose exchange in S. thermophilus [89], arginine/ornithine exchange in Pseudomonas aeruginosa [90], malate/lactate exchange in L. lactis [43].…”

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confidence: 99%