دورية
A novel membrane-associated threonine permease encoded by the tdcC gene of Escherichia coli
العنوان: | A novel membrane-associated threonine permease encoded by the tdcC gene of Escherichia coli |
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المؤلفون: | Sumantran, V N, Schweizer, H P, Datta, P |
المصدر: | Journal of Bacteriology; August 1990, Vol. 172 Issue: 8 p4288-4294, 7p |
مستخلص: | A novel L-threonine transport system is induced in Escherichia coli cells when incubated in amino acid-rich medium under anaerobic conditions. Genetic and biochemical analyses with plasmids harboring mutations in the anaerobically expressed tdcABC operon indicated that the tdcC gene product was responsible for L-threonine uptake. Competition experiments revealed that the L-threonine transport system is also involved in L-serine uptake and is partially shared for L-leucine transport; L-alanine, L-valine, and L-isoleucine did not affect L-threonine uptake. Transport of L-threonine was inhibited by the respiratory chain inhibitors KCN and carbonyl cyanide m-chlorophenylhydrazone and was Na+ independent. These results identify for the first time an E. coli gene encoding a permease specific for L-threonine-L-serine transport that is distinct from the previously described threonine-serine transport systems. A two-dimensional topological model predicted from the amino acid composition and hydropathy plot showed that the TdcC polypeptide appears to be an integral membrane protein with several membrane-spanning domains exhibiting a striking similarity with other bacterial permeases. |
قاعدة البيانات: | Supplemental Index |
تدمد: | 00219193 10985530 |
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DOI: | 10.1128/jb.172.8.4288-4294.1990 |