We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Asp-863 is a key residue for calcium-dependent activity of Escherichia coli RTX toxin α-haemolysin
- Authors
Cortajarena, Aitziber L.; Goñi, Félix M.; Ostolaza, Helena
- Abstract
α-Haemolysin is a protein toxin secreted by pathogenic strains of Escherichia coli and requires sub-millimolar Ca2+ for optimum lytic activity. As a member of the so-called RTX toxin family it contains a Gly-rich, Asp-rich Ca2+-binding domain, consisting of a series of nonapeptides repeated in tandem. Asp-863 is located immediately after the last-but-one nonapeptide. A mutant in which Asp-863 has been substituted by Gly displays a requirement for Ca2+ that is 100-fold higher than the wild-type. Membrane lytic activity, as well as a conformational change revealed through an increase in intrinsic fluorescence, and the appearance of Ca2+-bound protein monomers resolvable by fast protein liquid chromatography, are all three dependent on Ca2+ concentrations in the 2–20 mM range. Most RTX toxins have an Asp or Glu residue located at a position homologous to Asp-863, thus the key role of this residue for Ca2+ requirements of α-haemolysin may be a general feature of this family of toxins.
- Subjects
PHOSPHOLIPIDS; ESCHERICHIA coli
- Publication
FEBS Letters, 2003, Vol 546, Issue 2/3, p271
- ISSN
0014-5793
- Publication type
Article
- DOI
10.1016/S0014-5793(03)00595-7