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Aphanothece halophytica is a halotolerant alkaliphilic cyanobacterium which can grow in media of up to 3.0 M NaCl and pH 11. This cyanobacterium can synthesize betaine from glycine by three-step methylation using S-adenosylmethionine as a methyl donor. To unveil the mechanism of betaine uptake and efflux in this alkaliphile, we isolated and characterized a(More)
γ-Aminobutyric acid (GABA) is known as an inhibitory neurotransmitter in human, while in plants, GABA is an intermediate for amino acid metabolism and also is accumulated in response to a wide range of environmental stress. In the present study, GABA accumulation in Aphanothece halophytica was increased 2-fold in mid-log phase cells grown under salt stress(More)
Glutamate is a major free amino acid in cyanobacteria, but its transport properties remain largely unknown. In this study, we found that a halotolerant cyanobacterium, Aphanothece halophytica, contained a sodium dependent glutamate transporter (ApGltS). The deduced amino acid sequence of ApGltS exhibited low homology (18-19% identity) to GltS from(More)
The energetics of nitrate uptake by intact cells of the halotolerant cyanobacterium Aphanothece halophytica were investigated. Nitrate uptake was inhibited by various protonophores suggesting the coupling of nitrate uptake to the proton motive force. An artificially-generated pH gradient across the membrane (DeltapH) caused an increase of nitrate uptake. In(More)
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