The staphylococcal alpha-toxin pore has a flexible conformation

Article Article scientifique Article The staphylococcal alpha-toxin pore has a flexible conformation eng 1999 author Vecsey Semjen Beatrix 90585 author Knapp Stefan author Möllby Roland author Van Der Goot Grunberg Françoise G. 24466 4296-4302 10.1021/bi982472k 10194347 0006-2960 The alpha-toxin from Staphylococcus aureus undergoes several conformational changes from the time it is released from the bacterium to the moment it forms a channel in the plasma membrane of its target cell. It is initially a soluble monomer, which undergoes membrane binding and oligomerization into a heptameric ring and finally inserts into the lipid bilayer to form a pore. Here we have analyzed the stability of different forms of the alpha-toxin (monomer as well as heptamers in solution, bound to the membrane and membrane-inserted) by differential scanning calorimetry and limited proteolysis. Data presented here show that, in contrast to both the membrane-bound prepore complex and the monomer in solution, the membrane-inserted alpha-toxin channel does not undergo cooperative unfolding and is highly susceptible to proteases. These observations suggest that the channel has a looser conformation. Interestingly, resistance to proteases could be recovered upon solubilization of the channel, indicating that the loss of rigid tertiary packing only occurred upon membrane insertion. Far-UV CD data, however, suggest that the transmembrane beta-barrel must be stably folded and that therefore only the Cap and Rim domains of the channel are loosely packed. All together, our data show that the alpha-toxin channel is not a rigid complex within the membrane but adopts a rather flexible conformation. Dewey 540 28 Section de chimie et biochimie 14 false Biochemistry 38 14 26be3184-4912-4577-93a3-5c521632f98e Article (Published version) Restricted B.Vécsey-Semjén.pdf 143680 application/pdf restrictedAccess Faculté des sciences / Section de chimie et biochimie

Title	Published in	Access level	OA Policy	Year	Views	Downloads

The staphylococcal alpha-toxin pore has a flexible conformation	Biochemistry			1999	467	0

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Vecsey Semjen, Beatrix