Open AccessAntiparallel membrane topology of paired short‐chain chromate transport proteins in B acillus subtilis
Author(s) -
MartínezValencia Rene,
ReyesCortés Guadalupe,
RamírezDíaz Martha I.,
RiverosRosas Héctor,
Cervantes Carlos
Publication year - 2012
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2012.02661.x
Subject(s) - periplasmic space , bacillus subtilis , antiparallel (mathematics) , transmembrane protein , biochemistry , membrane topology , membrane protein , biology , peptide sequence , chemistry , escherichia coli , topology (electrical circuits) , membrane , genetics , gene , bacteria , physics , receptor , mathematics , quantum mechanics , combinatorics , magnetic field
Short‐chain monodomain family comprises pairs of membrane proteins of about 200 amino acid residues each that belong to the chromate ion transporter ( CHR ) superfamily. The short‐chain CHR homologous pair Chr3N / Chr3C from B acillus subtilis strain 168 confers chromate resistance only when both proteins are expressed. Membrane topology of the Chr3N and Chr3C proteins was determined in E scherichia coli by the analysis of translational fusions with reporter enzymes alkaline phosphatase and β‐galactosidase. Each short‐chain CHR protein was found to consist of five transmembrane segments with antiparallel orientation between them. The C terminus of Chr3N is located in the cytoplasm, whereas the C terminus of Chr3C is located in the periplasm. In silico analyses suggest that this antiparallel arrangement is shared by all protein members of the short‐chain CHR 3 subfamily and that the two Chr3N / Chr3C proteins might carry out distinct functions for the transport of chromate.