@article{TheinBondeBunikisetal.2012,
  author    = {Thein, Marcus and Bonde, Mari and Bunikis, Ignas and Denker, Katrin and Sickmann, Albert and Bergstr{\"o}m, Sven and Benz, Roland},
  title     = {DipA, a Pore-Forming Protein in the Outer Membrane of Lyme Disease Spirochetes Exhibits Specificity for the Permeation of Dicarboxylates},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-75809},
  year      = {2012},
  abstract  = {Lyme disease Borreliae are highly dependent on the uptake of nutrients provided by their hosts. Our study describes the identification of a 36 kDa protein that functions as putative dicarboxylate-specific porin in the outer membrane of Lyme disease Borrelia. The protein was purified by hydroxyapatite chromatography from Borrelia burgdorferi B31 and designated as DipA, for dicarboxylate-specific porin A. DipA was partially sequenced, and corresponding genes were identified in the genomes of B. burgdorferi B31, Borrelia garinii PBi and Borrelia afzelii PKo. DipA exhibits high homology to the Oms38 porins of relapsing fever Borreliae. B. burgdorferi DipA was characterized using the black lipid bilayer assay. The protein has a singlechannel conductance of 50 pS in 1 M KCl, is slightly selective for anions with a permeability ratio for cations over anions of 0.57 in KCl and is not voltage-dependent. The channel could be partly blocked by different di- and tricarboxylic anions. Particular high stability constants up to about 28,000 l/mol (in 0.1 M KCl) were obtained among the 11 tested anions for oxaloacetate, 2-oxoglutarate and citrate. The results imply that DipA forms a porin specific for dicarboxylates which may play an important role for the uptake of specific nutrients in different Borrelia species.},
  subject      = {Medizin},
  language  = {en}
}
@article{BeitzingerStefaniKronhardtetal.2012,
  author    = {Beitzinger, Christoph and Stefani, Caroline and Kronhardt, Angelika and Rolando, Monica and Flatau, Gilles and Lemichez, Emanuel and Benz, Roland},
  title     = {Role of N-Terminal His6-Tags in Binding and Efficient Translocation of Polypeptides into Cells Using Anthrax Protective Antigen (PA)},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-76325},
  year      = {2012},
  abstract  = {It is of interest to define bacterial toxin biochemical properties to use them as molecular-syringe devices in order to deliver enzymatic activities into host cells. Binary toxins of the AB7/8-type are among the most potent and specialized bacterial protein toxins. The B subunits oligomerize to form a pore that binds with high affinity host cell receptors and the enzymatic A subunit. This allows the endocytosis of the complex and subsequent injection of the A subunit into the cytosol of the host cells. Here we report that the addition of an N-terminal His6-tag to different proteins increased their binding affinity to the protective antigen (PA) PA63-channels, irrespective if they are related (C2I) or unrelated (gpJ, EDIN) to the AB7/8-family of toxins. His6-EDIN exhibited voltage-dependent increase of the stability constant for binding by a factor of about 25 when the trans-side corresponding to the cell interior was set to 270 mV. Surprisingly, the C. botulinum toxin C2II-channel did not share this feature of PA63. Cell-based experiments demonstrated that addition of an N-terminal His6-tag promoted also intoxication of endothelial cells by C2I or EDIN via PA63. Our results revealed that addition of His6-tags to several factors increase their binding properties to PA63 and enhance the property to intoxicate cells.},
  subject      = {Biologie},
  language  = {en}
}