1. Periplasmic loop P2 of the MalF subunit of the maltose ATP binding cassette transporter is sufficient to bind the maltose binding protein MalE.
- Author
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Jacso T, Grote M, Daus ML, Schmieder P, Keller S, Schneider E, and Reif B
- Subjects
- ATP-Binding Cassette Transporters genetics, Calorimetry, Cross-Linking Reagents chemistry, Crystallography, X-Ray, Cysteine chemistry, Databases, Protein, Escherichia coli genetics, Escherichia coli Proteins genetics, Maltose chemistry, Models, Molecular, Monosaccharide Transport Proteins genetics, Nuclear Magnetic Resonance, Biomolecular, Periplasmic Binding Proteins chemistry, Periplasmic Binding Proteins genetics, Phenanthrolines chemistry, Protein Binding physiology, Protein Conformation, Protein Structure, Secondary, Recombinant Proteins chemistry, Recombinant Proteins genetics, ATP-Binding Cassette Transporters chemistry, ATP-Binding Cassette Transporters metabolism, Escherichia coli enzymology, Escherichia coli Proteins chemistry, Escherichia coli Proteins metabolism, Monosaccharide Transport Proteins chemistry, Monosaccharide Transport Proteins metabolism, Periplasmic Binding Proteins metabolism, Protein Interaction Domains and Motifs physiology
- Abstract
The Escherichia coli maltose transporter belongs to the ATP binding cassette (ABC) transporter superfamily. Recently, the crystal structure of the full transporter MalFGK2 in complex with the maltose binding protein (MBP) was determined [Oldham, M. L., et al. (2007) Crystal structure of a catalytic intermediate of the maltose transporter. Nature 450, 515-522]. Using liquid-state NMR, we find that the periplasmic loop P2 of MalF (MalF-P2) folds independently in solution and adopts a well-defined tertiary structure which is similar to the one found in the crystal. MalF-P2 interacts with the maltose binding protein, independent of the transmembrane region of MalF and MalG with an affinity of 10-20 microM, in the presence and absence of substrate. Analysis of residual dipolar coupling (RDC) experiments shows that the conformation of the two individual domains of MalF-P2 is preserved in the absence of MalE and resembles the conformation in the X-ray structure. Upon titration of MalE to MalF-P2, the two domains of MalF-P2 change their relative orientation to accommodate the ligand. In particular, a conformational change of domain 2 of MalF-P2 is induced, which is distinct from the conformation found in the X-ray structure.
- Published
- 2009
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