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2bk2
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THE PREPORE STRUCTURE OF PNEUMOLYSIN, OBTAINED BY FITTING THE ALPHA CARBON TRACE OF PERFRINGOLYSIN O INTO A CRYO-EM MAP
Overview
The bacterial toxin pneumolysin is released as a soluble monomer that kills target cells by assembling into large oligomeric rings and forming pores in cholesterol-containing membranes. Using cryo-EM and image processing, we have determined the structures of membrane-surface bound (prepore) and inserted-pore oligomer forms, providing a direct observation of the conformational transition into the pore form of a cholesterol-dependent cytolysin. In the pore structure, the domains of the monomer separate and double over into an arch, forming a wall sealing the bilayer around the pore. This transformation is accomplished by substantial refolding of two of the four protein domains along with deformation of the membrane. Extension of protein density into the bilayer supports earlier predictions that the protein inserts beta hairpins into the membrane. With an oligomer size of up to 44 subunits in the pore, this assembly creates a transmembrane channel 260 A in diameter lined by 176 beta strands.
About this Structure
2BK2 is a Single protein structure of sequence from Clostridium perfringens. Full crystallographic information is available from OCA.
Reference
Structural basis of pore formation by the bacterial toxin pneumolysin., Tilley SJ, Orlova EV, Gilbert RJ, Andrew PW, Saibil HR, Cell. 2005 Apr 22;121(2):247-56. PMID:15851031
Page seeded by OCA on Thu Mar 20 16:02:56 2008
