CHARACTERIZATION OF THE SPECIFIC PYRUVATE TRANSPORT-SYSTEM IN ESCHERICHIA-COLI K-12
CHARACTERIZATION OF THE SPECIFIC PYRUVATE TRANSPORT-SYSTEM IN ESCHERICHIA-COLI K-12
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DOI：
10.1128/jb.169.1.380-385.1987
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发表时间：
1987-01-01
影响因子：
3.2
通讯作者：
COOK, RA
中科院分区：
文献类型：
--
作者：
LANG, VJ;LEYSTRALANTZ, C;COOK, RA
A mutant of Escherichia coli K-12 lacking pyruvate dehydrogenase and phosphoenolpyruvate synthase was used to study the transport of pyruvate by whole cells. Uptake of pyruvate was maxima in mid-log phase cells, with a Michaelis constant for transport of 20 .mu.M. Pretreatment of the cells with respiratory chain poisons or uncouplers, except for arsenate, inhibited transport up to 95%. Lactate and alanine were competitive inhibitors, but nonphysiological concentrations. The synthetic analogs 3-bromopyruvate and pyruvic acid methyl ester inhibited competitively. The uptake of pyruvate was also characterized in membrane vesicles from wild-type E. coli K-2. Transport required an artificial electron donor system, phenazine methosulfate and sodium ascorbate. Pyruvate was concentrated in vesicles 7- to 10-fold over the external concentration, with a Michaelis constant of 15 .mu.M. Energy poisons, except arsenate, inhibited the transported of pyruvate. Synthetic analogs such as 3-bromopyruvate were competitive inhibitors of transport. Lactate initially appeared to be a competitive inhibitor of pyruvate transport in vesicles, but this was a result of oxidation of lactate to pyruvate. The results indicate that uptake of pyruvate in E. coli is via a specific active transport system.
