Channel formation by the binding component of Clostridium botulinum C2 toxin: glutamate 307 of C2II affects channel properties in vitro and pH-dependent C2I translocation in vivo
| Autor: | Dagmar Blöcker, Klaus Aktories, Holger Barth, Roland Benz, Christoph Bachmeyer |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
Botulinum Toxins
Recombinant Fusion Proteins Mutant Lipid Bilayers Glutamic Acid Gating CHO Cells Biology In Vitro Techniques Cleavage (embryo) Biochemistry Ion Channels Cell membrane Cricetinae Chlorocebus aethiops medicine Clostridium botulinum Escherichia coli Animals Humans Lipid bilayer Vero Cells Sequence Deletion chemistry.chemical_classification ADP Ribose Transferases Binding Sites Electric Conductivity Chloroquine Hydrogen-Ion Concentration Amino acid Anti-Bacterial Agents Cytosol Membrane medicine.anatomical_structure chemistry Mutation Biophysics Mutagenesis Site-Directed Macrolides Poly(ADP-ribose) Polymerases Ion Channel Gating Protein Binding |
| Zdroj: | Biochemistry. 42(18) |
| ISSN: | 0006-2960 |
| Popis: | The binding component (C2II) of the binary Clostridium botulinum C2 toxin mediates transport of the actin ADP-ribosylating enzyme component (C2I) into the cytosol of target cells. C2II (80 kDa) is activated by trypsin cleavage, and proteolytically activated C2II (60 kDa) oligomerizes to heptamers in solution. Activated C2II forms channels in lipid bilayer membranes which are highly cation selective and voltage-gated. A role for this channel in C2I translocation across the cell membrane into the cytosol is discussed. Amino acid residues 303-331 of C2II contain a conserved pattern of alternating hydrophobic and hydrophilic residues, which likely facilitates membrane insertion and channel formation by creating two antiparallel beta-strands. Some of the residues are in strategic positions within the putative C2II channel, in particular, glutamate 307 (E307) localized in its center and glycine 316 (G316) localized on the trans side of the membrane. Here, single-lysine substitutions of these amino acids and the double mutant E307K/G316K of C2II were analyzed in vivo and in artificial lipid bilayer experiments. The pH dependence of C2I transport across cellular membranes was altered, and a pH of |
| Databáze: | OpenAIRE |
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