Essential lysine residues within transmembrane helix 1 of diphtheria toxin facilitate COPI binding and catalytic domain entry.

ABSTRACT: The translocation of the diphtheria toxin catalytic domain from the lumen of early endosomes into the cytosol of eukaryotic cells is an essential step in the intoxication process. We have previously shown that the in vitro translocation of the catalytic domain from the lumen of toxin pre-loaded endosomal vesicles to the external medium requires the addition of cytosolic proteins including coatomer protein complex I (COPI) to the reaction mixture. Further, we have shown that transmembrane helix 1 plays an essential, but as yet undefined role in the entry process. We have used both site-directed mutagenesis and a COPI complex precipitation assay to demonstrate that interaction(s) between at least three lysine residues in transmembrane helix 1 are essential for both COPI complex binding and t

SUBMITTER: Trujillo C 

PROVIDER: S-EPMC4113555 | biostudies-literature | 2010 May

REPOSITORIES: biostudies-literature