期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1973
卷号：70
期号：5
页码：1514-1518
DOI：10.1073/pnas.70.5.1514
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The ability of either glucose or D-lactate to energize active transport of amino acids in E. coli was studied in starved cells blocked at specific sites of energy metabolism. Proline uptake could be driven by either oxidative or substrate-level processes. The oxidative pathway was sensitive to cyanide but not to arsenate, and operated normally in a mutant deficient in the Ca, Mg-dependent ATPase. The substrate-level pathway, which was active with glucose but not with D-lactate as the carbon source, was sensitive to arsenate but not to cyanide, and required a functional ATPase. Uncouplers prevented the utilization of energy for proline uptake by either pathway. Energy coupling for glutamine uptake was quite different. The oxidative pathway was sensitive to cyanide and uncouplers and, in contrast with proline, required an active ATPase. The glycolytic component was resistant to cyanide and uncouplers, and functioned normally in the ATPase mutant. Arsenate abolished glutamine transport energized by either pathway. The results suggest that proline transport is driven directly by an energy-rich membrane state, which can be generated by either electron transport or ATP hydrolysis. Glutamine uptake, on the other hand, is apparently driven directly by phosphate-bond energy formed by way of oxidative or substrate-level phosphorylations.
关键词：inhibitors ; mutants ; ATP ; energized membrane state ; starvation
