title: Periplasmic loop P2 of the MalF subunit of the maltose ATP binding cassette transporter is sufficient to bind the maltose binding protein MalE.
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.
authors.affiliation: Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany.
authors.forename: Tomas
authors.initials: T
authors.lastname: Jacso
authors.forename: Mathias
authors.initials: M
authors.lastname: Grote
authors.forename: Martin L
authors.initials: ML
authors.lastname: Daus
authors.forename: Peter
authors.initials: P
authors.lastname: Schmieder
authors.forename: Sandro
authors.initials: S
authors.lastname: Keller
authors.forename: Erwin
authors.initials: E
authors.lastname: Schneider
authors.forename: Bernd
authors.initials: B
authors.lastname: Reif
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002151:Calorimetry; D003432:Cross-Linking Reagents / Q000737:chemistry; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000737:chemistry; D030562:Databases, Protein; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008320:Maltose / Q000737:chemistry; D008958:Models, Molecular; D009004:Monosaccharide Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019906:Nuclear Magnetic Resonance, Biomolecular; D033902:Periplasmic Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010618:Phenanthrolines / Q000737:chemistry; D011485:Protein Binding / Q000502:physiology; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs / Q000502:physiology*; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics
chemical_list: D018528:ATP-Binding Cassette Transporters; D003432:Cross-Linking Reagents; D029968:Escherichia coli Proteins; C461619:MalE protein, E coli; C461639:MalF protein, E coli; D009004:Monosaccharide Transport Proteins; D033902:Periplasmic Binding Proteins; D010618:Phenanthrolines; D011994:Recombinant Proteins; C461599:maltose transport system, E coli; C014741:bis(1,10-phenanthroline)copper(2+) ion; D008320:Maltose; D003545:Cysteine