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|標題:||Glycine betaine transport in the obligate halophilic archaeon Methanohalophilus portucalensis|
|期刊/報告no：:||Journal of Bacteriology, Volume 182, Issue 17, Page(s) 5020-5024.|
|摘要:||Transport of the osmoprotectant glycine betaine was investigated using the glycine betaine-synthesizing microbe Methanohalophilus portucalensis (strain FDF1), since solute uptake for this class of obligate halophilic methanogenic Archaea has not been examined. Betaine uptake followed a Michaelis-Menten relationship,,vith an observed K-t of 23 mu M and a V-max of 8 nmol per min per mg of protein. The transport system was highly specific for betaine: choline, proline, and dimethylglycine did not significantly compete for [C-14]betaine uptake. The proton-conducting uncoupler 2,4-dinitrophenol and the ATPase inhibitor N,N-dicyclohexylcarbodiimide both inhibited glycine betaine uptake. Growth of cells in the presence of 500 mu M betaine resulted in faster cell growth due to the suppression of the de novo synthesis of the other compatible solutes, alpha-glutamate, beta-glutamine, and N-e-acetyl-beta-lysine. These investigations demonstrate that this model halophilic methanogen, M. portucalensis strain FDF1, possesses a high-affinity and highly specific betaine transport system that allows it to accumulate this osmoprotectant from the environment in lien of synthesizing this or other osmoprotectants under high-salt growth conditions.|
|Appears in Collections:||生命科學系所|
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