Citrate mediated iron transport across the cytoplasmic membrane of E. coli

• Applicant: Professor Dr. Volkmar Braun
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms
• Term: from 2004 to 2007
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5430332

ABC transporters are the most frequently occurring transport systems in prokaryotes and eukaryotes. They show a high similarity in their basic design and function. The first crystal structure of an ABC transporter has recently been determined. It transports vitamin B12 into E.coli. The separately determined crystal structures of the periplasamic binding protein and of the cytoplasmic membrane transport protein suggest a specific model of how the two proteins interact which is not known for any of the bacterial ABC transporters. The interaction model will be experimentally examined with the citrate mediated iron transport system which is similar to that of vitamin B12. The choice of the citrate mediated iron transport comes from the fact that we have extensively characterized this transport system, in particular its novel mechanism of transmembrane transcription control. Various amino acid substitutions will be constructed including cysteine derivatives which allow studying specific interactions by spontaneous formation of disulfide bonds. Transport activities and substrate independent ATP hydrolysis of various disulfide linked derivatives will be tested to gain insights of how the transport proteins form a transport active complex.

• DFG Programme: Research Grants