1. Effect of Two Polyamine Toxins on the Bacterial Porin OmpF
- Author
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Anne H. Delcour and Arnaud Baslé
- Subjects
Models, Molecular ,Protein Conformation ,Mutant ,Biophysics ,Porins ,Spider Venoms ,Spermine ,Wasp Venoms ,Biology ,medicine.disease_cause ,Biochemistry ,Membrane Potentials ,chemistry.chemical_compound ,Bacterial Proteins ,Joro toxin ,Computer Graphics ,Escherichia coli ,Polyamines ,medicine ,Molecular Biology ,Cell Membrane ,Philanthotoxin ,Cell Biology ,biochemical phenomena, metabolism, and nutrition ,Spider toxin ,chemistry ,Porin ,bacteria ,Polyamine - Abstract
Spermine, a polyamine based on a 12-carbon motif, is an effective inhibitor of E. coli OmpF porin. Here we study the inhibition of porin by two polyamine toxins commonly used as modulators of polyamine-sensitive channels: Philanthotoxin-433 (PhTX) from wasp venom and Joro spider toxin (JSTX). Both are highly asymmetric molecules, with at one end a 12-carbon chain polyamine targeting the molecule to the porin constriction zone, and at the other end large aromatic groups conferring to this extremity a size in the order of the OmpF constriction zone. Here we report that PhTX, but not Joro toxin, induces a high degree of flickering in the OmpF-mediated current. The effect is concentration and voltage-dependent, and greatly diminished in a mutant lacking D113 on the constriction loop, a residue previously shown to be required for spermine sensitivity. Possible reasons for the distinct sensitivity of OmpF to PhTX and Joro toxin are discussed.
- Published
- 2001
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