gamma-Aminobutyric acid uptake by a bacterial system with neurotransmitter binding characteristics.

AUTOR(ES)

Guthrie, G D

RESUMO

gamma-Aminobutyric acid (GABA), an amino acid, has been found in every class of living organisms. In higher organisms, GABA is a neurotransmitter and binds with high affinity and specificity to GABA receptors on neurons in a sodium-independent reaction that is saturable. The role of GABA in organisms lacking nervous tissue is not known. This report describes, in a strain of Pseudomonas fluorescens, a GABA uptake system with binding characteristics like those of the GABA (type A) brain receptor. The binding was saturable and specific for GABA, was sodium-independent, was of high affinity (Km = 65 nM), and was inhibited competitively by muscimol, a potent GABA analogue. The bacterial GABA system included a homogeneous binding site, and no cooperative interaction was found between sites. To our knowledge, such a system for GABA, or other neurotransmitters, in a bacterium has not been reported.

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