%0 Journal Article
%T The Sticholysin I mutants St I E2C and St I R52C show similar binding to liposomal vesicles but differ in their permeabilizing activity
%A L¨®pez
%A Aracelys
%A Valle
%A Aisel
%A Pedrera
%A Lohans
%A Mart¨ªnez
%A Diana
%A Fando
%A Rafael
%A Schreier
%A Shirley
%A ¨¢lvarez
%A Carlos
%A Lanio
%A Mar¨ªa E
%A Pazos
%A Fabiola
%J Biotecnolog£¿-a Aplicada
%D 2011
%I Scientific Electronic Library Online
%X the mechanism of pore formation by actinoporins is a multistep process, involving binding of water soluble monomer to membrane and subsequent oligomerization of monomers on the membrane surface, forming a functional pore. however, molecular details of membrane insertion mechanism and oligomerization are not clear. a phosphocholine-binding site and a surface cluster of aromatic rings, together with a basic region, are important to the initial interaction with membrane and the n-terminal region is relevant in the pore formation. aiming to deepen into the structure-function relationship in sticholysins, we designed and produced two cys mutants of recombinant sticholysin i (rst i) in relevant functional regions for membrane interaction: st i e2c (in the n-terminal region) and st i r52c (in the membrane binding site). conformational studies suggested that the replacement of glu-2 and arg-52 by a cys residue in rst i not noticeably changes protein conformation as assessed by fluorescence and cd spectroscopy, the first change not affecting toxin£¿s permeabilizing ability. the relative decrease in the pore forming capacity of st i r52c is not related with a smaller binding capacity of this mutant to membrane. in summary, st i e2c and st i r52c retain the main conformational properties of the wild type and show similar binding to liposomal vesicles while differing in their permeabilizing activity. st i e2c and st i r52c constitute good tools to study those steps of the permeabilizing mechanism of sticholysins that take place after binding to membrane, using thiol-specific probes such as fluorescent and spin labels.
%K pore-forming toxin
%K actinoporin
%K membrane-protein interaction.
%U http://scielo.sld.cu/scielo.php?script=sci_abstract&pid=S1027-28522011000100003&lng=en&nrm=iso&tlng=en