• Structural basis for complex formation between human IRSp53 and the translocated intimin receptor Tir of enterohemorrhagic E. coli.

      de Groot, Jens C; Schlüter, Kai; Carius, Yvonne; Quedenau, Claudia; Vingadassalom, Didier; Faix, Jan; Weiss, Stefanie M; Reichelt, Joachim; Standfuss-Gabisch, Christine; Lesser, Cammie F; et al. (2011-09-07)
      Actin assembly beneath enterohemorrhagic E. coli (EHEC) attached to its host cell is triggered by the intracellular interaction of its translocated effector proteins Tir and EspF(U) with human IRSp53 family proteins and N-WASP. Here, we report the structure of the N-terminal I-BAR domain of IRSp53 in complex with a Tir-derived peptide, in which the homodimeric I-BAR domain binds two Tir molecules aligned in parallel. This arrangement provides a protein scaffold linking the bacterium to the host cell's actin polymerization machinery. The structure uncovers a specific peptide-binding site on the I-BAR surface, conserved between IRSp53 and IRTKS. The Tir Asn-Pro-Tyr (NPY) motif, essential for pedestal formation, is specifically recognized by this binding site. The site was confirmed by mutagenesis and in vivo-binding assays. It is possible that IRSp53 utilizes the NPY-binding site for additional interactions with as yet unknown partners within the host cell.
    • Structures of the nucleotide-binding domain of the human ABCB6 transporter and its complexes with nucleotides.

      Haffke, Matthias; Menzel, Anja; Carius, Yvonne; Jahn, Dieter; Heinz, Dirk W; Helmholtz Zentrum für Infektionsforschung, Braunschweig, Germany. (2010-09)
      The human ATP-binding cassette (ABC) transporter ABCB6 is involved in haem-precursor transport across the mitochondrial membrane. The crystal structure of its nucleotide-binding domain (NBD) has been determined in the apo form and in complexes with ADP, with ADP and Mg(2+) and with ATP at high resolution. The overall structure is L-shaped and consists of two lobes, consistent with other reported NBD structures. Nucleotide binding is mediated by the highly conserved Tyr599 and the Walker A motif, and induces notable structural changes. Structural comparison with other structurally characterized NBDs and full-length ABC transporters gives the first insight into the possible catalytic mechanism of ABCB6 and the role of the N-terminal helix alpha(1) in full-length ABCB6.