[NMR paper] Solution NMR analysis of the interaction between the actinoporin Sticholysin I and DHPC micelles. Correlation with backbone dynamics.

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Solution NMR analysis of the interaction between the actinoporin Sticholysin I and DHPC micelles. Correlation with backbone dynamics.

Related Articles Solution NMR analysis of the interaction between the actinoporin Sticholysin I and DHPC micelles. Correlation with backbone dynamics.

Proteins. 2013 Nov 12;

Authors: Castilla AL, Santos FP, Schreier S, Pires JR

Abstract
Sticholysin I (StI), an actinoporin expressed as a water-soluble protein by the sea anemone Stichodactyla helianthus, binds to natural and model membranes, forming oligomeric pores. It is proposed that the first event of a multistep pore formation mechanism consists of the monomeric protein attachment to the lipid bilayer. To date there is no high-resolution structure of the actinoporin pore or other membrane-bound form available. Here we evaluated StI:micelle complexes of variable lipid composition to look for a suitable model for NMR studies. Micelles of pure or mixed lysophospholipids and of dihexanoyl phosphatidylcholine (DHPC) were examined. The StI:DHPC micelle was found to be the best system, yielding a stable sample and good quality spectra. A comprehensive chemical shift perturbation analysis was performed to map the StI membrane recognition site in the presence of DHPC micelles. The region mapped (residues F(51) , R(52) , S(53) in loop 3; F(107) , D(108) , Y(109) , W(111) , Y(112) , W(115) in loop 7; Q12(9) , Y(132) , D(134) , M(135) , Y(136) , Y(137) , G(138) in helix-?2) is in agreement with previously reported data, but additional residues were found to interact, especially residues V(81) , A(82) , T(83) , G(84) in loop 5, and A(85) , A(87) in strand-?5. Backbone dynamics measurements of StI free in solution and bound to micelles highlighted the relevance of protein flexibility for membrane binding and suggested that a conformer selection process may take place during protein-membrane interaction. We conclude that the StI:DHPC micelles system is a suitable model for further characterization of an actinoporin membrane-bound form by solution NMR. © Proteins 2013;. © 2013 Wiley Periodicals, Inc.


PMID: 24218049 [PubMed - as supplied by publisher]



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