Nucleotide sequence and expression in Escherichia coli of the Lactococcus lactis citrate permease gene

J Bacteriol. 1990 Oct;172(10):5789-94. doi: 10.1128/jb.172.10.5789-5794.1990.


The plasmid-encoded citrate determinant of the Lactococcus lactis subsp. lactis var. diacetylactis NCDO176 was cloned and functionally expressed in a Cit- Escherichia coli K-12 strain. From deletion derivative analysis, a 3.4-kilobase region was identified which encodes the ability to transport citrate. Analysis of proteins encoded by the cloned fragment in a T7 expression system revealed a 32,000-dalton protein band, which correlated with the ability of cells to transport citrate. Energy-dependent [1,5-14C]citrate transport was found with membrane vesicles prepared from E. coli cells harboring the citrate permease-expressing plasmid. The gene encoding citrate transport activity, citP, was located on the cloned fragment by introducing a site-specific mutation that abolished citrate transport and resulted in a truncated form of the 32,000-dalton expression product. The nucleotide sequence for a 2.2-kilobase fragment that includes the citP gene contained an open reading frame of 1,325 base pairs coding for a very hydrophobic protein of 442 amino acids, which shows no sequence homology with known citrate carriers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins*
  • Base Sequence
  • Cell Membrane / enzymology
  • Citrates / metabolism
  • Cloning, Molecular / methods
  • Escherichia coli / genetics
  • Genes, Bacterial*
  • Kinetics
  • Lactococcus lactis / enzymology
  • Lactococcus lactis / genetics*
  • Membrane Transport Proteins / genetics*
  • Molecular Sequence Data
  • Organic Anion Transporters*
  • Proline / metabolism
  • Restriction Mapping


  • Bacterial Proteins
  • Citrates
  • Membrane Transport Proteins
  • Organic Anion Transporters
  • citP protein, Lactococcus lactis
  • Proline

Associated data

  • GENBANK/M58694