title: Cloning, sequencing, and expression in escherichia coli of OxlT, the oxalate:formate exchange protein of Oxalobacter formigenes.
abstract: OxlT is the oxalate/formate exchange protein that represents the vectorial component of a proton-motive metabolic cycle in Oxalobacter formigenes. Here we report the cloning and sequencing of OxlT and describe its expression in Escherichia coli. The OxlT amino acid sequence specifies a polytopic hydrophobic protein of 418 residues with a mass of 44,128 daltons. Analysis of hydropathy and consideration of the distribution of charged residues suggests an OxlT secondary structure having 12 transmembrane segments, oriented so that the N and C termini face the cytoplasm. Expression of OxlT in E. coli coincides with appearance of a capacity to carry out the self-exchange of oxalate and the heterologous, electrogenic exchange of oxalate with formate. The unusually high velocity of OxlT-mediated transport is also preserved in E. coli. We conclude that the essential features of OxlT are retained on its expression in E. coli.
authors.affiliation: Department of Physiology, Johns Hopkins Medical School, Baltimore, Maryland 21205, USA.
authors.forename: K
authors.initials: K
authors.lastname: Abe
authors.forename: Z S
authors.initials: ZS
authors.lastname: Ruan
authors.forename: P C
authors.initials: PC
authors.lastname: Maloney
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001483:Base Sequence; D001692:Biological Transport; D002352:Carrier Proteins; D003001:Cloning, Molecular; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000235:genetics; D005561:Formates / Q000378:metabolism*; D006089:Gram-Negative Anaerobic Bacteria / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D010070:Oxalates / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; D005561:Formates; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D010070:Oxalates; C099549:OxlT protein, bacteria; C030544:formic acid