Three-dimensional structure of a bacterial oxalate transporter.
The major facilitator superfamily (MFS) represents one of the largest classes of evolutionarily related membrane transporter proteins. Here we present the three-dimensional structure at 6.5 A resolution of a bacterial member of this superfamily, OxlT. The structure, derived from an electron crystallographic analysis of two-dimensional crystals, reveals that the 12 helices in the OxlT molecule are arranged around a central cavity, which is widest at the center of the membrane. The helices divide naturally into three groups: a peripheral set comprising helices 3, 6, 9 and 12; a second set comprising helices 2, 5, 8 and 11 that faces the central substrate transport pathway across most of the length of the membrane; and a third set comprising helices 1, 4, 7 and 10 that participate in the pathway either on the cytoplasmic side (4 and 10) or on the periplasmic side (1 and 7). Overall, the architecture of the protein is remarkably symmetric, providing a compelling molecular explanation for the ability of such transporters to carry out bi-directional substrate transport.
Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Teruhisa
T
Hirai
Jürgen A W
JA
Heymann
Dan
D
Shi
Rafiquel
R
Sarker
Peter C
PC
Maloney
Sriram
S
Subramaniam
D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D026901:Membrane Transport Proteins; D008958:Models, Molecular; D019815:Oxalic Acid / Q000378:metabolism*; D020624:Oxalobacter formigenes / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D055672:Static Electricity
D001426:Bacterial Proteins; D002352:Carrier Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C099549:OxlT protein, bacteria; D019815:Oxalic Acid