A novel membrane-associated threonine permease encoded by the tdcC gene of Escherichia coli

V. N. Sumantran, H. P. Schweizer, P. Datta

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


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-threonie 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 result 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.

Original languageEnglish (US)
Pages (from-to)4288-4294
Number of pages7
JournalJournal of Bacteriology
Issue number8
StatePublished - 1990
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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