Helena Ostolaza

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Familial hypercholesterolemia (FH) is a common autosomal codominant disease with a frequency of 1:500 individuals in its heterozygous form. The genetic basis of FH is most commonly mutations within the LDLR gene. Assessing the pathogenicity of LDLR variants is particularly important to give a patient a definitive diagnosis of FH. Current studies of LDLR(More)
alpha-haemolysin, an extracellular protein toxin of Escherichia coli, is known to disrupt eukaryotic cell membranes. In spite of genetic evidence of Ca(2+)-binding motifs in its sequence, conflicting results are found in the literature on the requirement of divalent cations for the membranolytic activity of the toxin. Moreover, Ca(2+)-binding sites have not(More)
A synthetic peptide (23 residues) that includes the antibacterial and lipopolysaccharide-binding regions of human lactoferricin, an antimicrobial sequence of lactoferrin, was used to study its action on cytoplasmic membrane of Escherichia coli 0111 and E. coli phospholipid vesicles. The peptide caused a depolarization of the bacterial cytoplasmic membrane,(More)
Adenylate cyclase toxin (ACT) is secreted by Bordetella pertussis, the bacterium causing whooping cough. ACT is a member of the RTX (repeats in toxin) family of toxins, and like other members in the family, it may bind cell membranes and cause disruption of the permeability barrier, leading to efflux of cell contents. The present paper summarizes studies(More)
alpha-Haemolysin interaction with model membranes has been investigated by a 2-fold procedure. First, protein binding has been measured, by a direct method as well as through changes in the intrinsic fluorescence of the protein when incubated with liposomes and divalent cations. Then, the above results have been correlated with the protein lytic activity.(More)
Alpha-Hemolysin is an extracellular protein toxin (107 kDa) produced by some pathogenic strains of Escherichia coli. Although stable in aqueous medium, it can bind to lipid bilayers and produce membrane disruption in model and cell membranes. Previous studies had shown that toxin binding to the bilayer did not always lead to membrane lysis. In this paper,(More)
Adenylate cyclase toxin (ACT), a 200 kDa protein, is an essential virulence factor for Bordetella pertussis, the bacterium that causes whooping cough. ACT is a member of the pore-forming RTX (repeats-in-toxin) family of proteins that share a characteristic calcium-binding motif of Gly- and Asp-rich nonapeptide repeats and a marked cytolytic or cytotoxic(More)
Recombinant Nef-protein of HIV-1 Bru derived from Escherichia coli revealed heparin-binding activity. This property was used to purify the Nef-protein by a one-step procedure, yielding about 90% homogenous Nef-protein as evaluated by silver staining. The Nef-protein was soluble without denaturing agents. Native folding of Nef was demonstrated with(More)
alpha-Haemolysin is an extracellular protein toxin (approximately 107 kDa) secreted by Escherichia coli that acts at the level of the plasma membranes of target eukaryotic cells. The nature of the toxin interaction with the membrane is not known at present, although it has been established that receptor-mediated binding is not essential. In this work, we(More)
The effects of a variety of detergents (non-ionic, ionic and bile derivatives) on B16 melanoma cells have been examined. Two main effects can be clearly differentiated: loss of cell viability and cell lysis. Under our conditions, cell-surfactant interaction is highly dependent on the nature of the amphiphile (more specifically, on its critical micellar(More)