A unique type of GABA binding by Mycobacterium leprae.
Neurotropism is one of the unusual properties of Mycobacterium leprae. The organism contains glutamic acid decarboxylase that generates gamma-amino-butyric acid (GABA) which is an inhibitory neurotransmitter. The binding of GABA by M. leprae in vitro was studied by using 3H-GABA as substrate. The bacteria had high-affinity binding sites for the amino acid. The uptake was a specific saturable process with a Km of 66.7 pM, pH optimum of 7.3 and a temperature optimum of 37 degrees C. The binding did not seem to be time-dependent, being complete in about 5 min. None of the known antagonists and agonists of GABA uptake by neurons, showed any significant effect on M. leprae; the receptors in the bacteria are apparently of a non-neuronal type, and different from those reported in spermatozoa and Pseudomonas.
Prabhakaran
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Laboratory Research Branch, Hansen's Disease Center, U.S. Public Health Service, Carville, Louisiana 70721.
Harris
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EB
Randhawa
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B
D000818:Animals; D001135:Armadillos; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009166:Mycobacterium leprae / Q000378:metabolism*; D011963:Receptors, GABA-A / Q000187:drug effects; D013696:Temperature; D013997:Time Factors; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid