What question did this study set out to answer?

To determine whether the AspT carrier in Lactobacillus subsp. M3 mediates electrogenic precursor-product exchange of aspartate and alanine to operate a proton-motive metabolic cycle.

February 1, 1996Journal of Biological ChemistryOpen Access

Exchange of Aspartate and Alanine

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To determine whether the AspT carrier in Lactobacillus subsp. M3 mediates electrogenic precursor-product exchange of aspartate and alanine to operate a proton-motive metabolic cycle.
Extracted Lactobacillus subsp. M3 membranes using 1.25% octyl glucoside supplemented with 0.4% Escherichia coli phospholipid and 20% glycerol.
Reconstituted functional AspT carrier proteins into proteoliposomes loaded with either aspartate or alanine.
Measured transport kinetics and electrical potential sensitivity using radiolabeled [3H]aspartate uptake and thermal inactivation protection assays.
Aspartate-loaded proteoliposomes mediated homologous self-exchange with a Kt of 0.4 mM, which remained unaffected by potassium/proton ionophores or Na+, K+, and Mg2+ cations.
Alanine-loaded proteoliposomes mediated heterologous antiport of [3H]aspartate, an exchange that was stimulated by inside-positive and inhibited by inside-negative membrane potential.
Direct interaction with a single functional carrier unit was confirmed as pre-incubation with aspartate (KD = 0.3 mM) or alanine (KD ≥ 10 mM) prevented thermal inactivation at 37°C.

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Implication

In vitro study demonstrates electrogenic aspartate and alanine exchange by AspT in proteoliposomes, supporting a proton-motive metabolic cycle in Lactobacillus.

Cite This Study

Abe et al. (1996) studied this question.

synapsesocial.com/papers/6a722360b27f15817827f317 https://doi.org/10.1074/jbc.271.6.3079

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Implication

In vitro study demonstrates electrogenic aspartate and alanine exchange by AspT in proteoliposomes, supporting a proton-motive metabolic cycle in Lactobacillus.

Exchange of Aspartate and Alanine

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Discussion

Implication

Cite This Study

Exchange of Aspartate and Alanine

Key Points

Discussion

Implication

Cite This Study

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