E. coli protein structure in major Science article uses data from DOE synchrotrons


The structure of a key membrane-spanning transporter protein in the bacterium E. coli is reported in Science for May 10, 2002. The protein, vitamin B-12 importer BtuCD, is a member of a class of more than a thousand known proteins, called ABC transporters, that import or export specific chemical species into or out of cells. These proteins are implicated in a number of diseases, including cystic fibrosis, and are involved in development of multidrug resistance in cancer cells. Gaining knowledge of the exact structure of these transporters is thus a high priority for structural molecular biology research, as such structures would enable explaining how a given transporter selects the specific chemical compound(s) it transports. The new article reports the first structure with sufficient spatial resolution, 3.2 Å, to locate all of the components of an ABC transporter. The three-dimensional structure shows the locations of the four subunits of the protein in relationship to each other and also precisely positions the many helical and strand-like portions of the subunits. The structure is used by the authors, Kaspar Locher, Allen Lee, and Douglas Rees of the California Institute of Technology, to develop a mechanism for how BtuCD imports vitamin B-12 into E. coli. The authors acknowledge use of the Stanford Synchrotron Radiation Laboratory (SSRL), the Advanced Photon Source (APS), the Advanced Light Source, and the National Synchrotron Light Source in crystal screening and data collection. The actual high resolution data were obtained at the BER-funded stations at SSRL and the APS.