Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 1992 May 5;267(13):8971-6.

Nucleotide sequence and functional properties of a sodium-dependent citrate transport system from Klebsiella pneumoniae

Affiliations
  • PMID: 1577734
Free article

Nucleotide sequence and functional properties of a sodium-dependent citrate transport system from Klebsiella pneumoniae

M E van der Rest et al. J Biol Chem. .
Free article

Abstract

The gene of the sodium-dependent citrate transport system from Klebsiella pneumoniae (citS) is located on plasmid pES3 (Schwarz, E., and Oesterhelt, D. (1985) EMBO J. 4, 1599-1603) and encodes a 446-amino acid protein. Transport of citrate via this citrate transport protein (CitS) is dependent on the presence of sodium ions and is inhibited by magnesium ions. The delta pH (pH gradient across the membrane) is the major driving force for uptake. It is postulated that, in analogy with the proton-dependent citrate carrier (CitH) of K. pneumoniae (van der Rest, M. E., Abee, T., Molenaar, D., and Konings, W. N. (1990) Eur. J. Biochem. 195, 71-77), only one of the protonated species of citrate is recognized by CitS and that citrate is translocated across the membrane in symport with protons and sodium ions. The hydrophobicity profile of CitS suggests that the protein is very hydrophobic and contains 12 membrane-spanning segments. These segments are not centered around a hydrophilic core as has been suggested for other transport proteins, but the protein is asymmetrical with seven transmembrane segments in front of a large hydrophilic loop and five after this loop. The amino acid sequence is highly similar to a citrate transport system of Lactococcus lactis subsp. lactis var. diacetylactis (CitP) (David, S., van der Rest, M. E., Driessen, A. J. M., Simons, G., and de Vos, W. M. (1990) J. Bacteriol. 172, 5789-5794) and less similar to CitH of K. pneumoniae. We conclude that the citS gene of K. pneumoniae encodes a sodium-dependent citrate transport system that belongs to a novel subclass of transport proteins.

PubMed Disclaimer

Similar articles

Cited by

Publication types

LinkOut - more resources