Polymerization of flagellin into P-filament in the presence of deoxycholate

Abstract

1. 1. A membrane fraction or its soluble fraction derived from deflagellated cells of a Salmonella strain initiates polymerization of flagellin into “P-filaments” which differ in many respects from flagellar filaments 1,2. In this paper it is shown that P-filaments may also be formed in the presence of deoxycholate and other bile salts. 2. 2. Optimal temperature for deoxycholate-initiated polymerization was about 60°C, which was close to that for polymerization initiated by the addition of soluble fraction (65°C). 3. 3. Electron microscopic comparison between two preparations of filaments formed in the presence of deoxycholate and soluble fraction showed that they were morphologically indistinguishable. Under various extreme conditions, the two preparations of filaments had similar high stabilities. 4. 4. To initiate polymerization, taurocholate was slightly less effective than deoxycholate, and glycocholate and cholate were much less effective than the above two. 5. 5. When filaments formed in the presence of deoxycholate were washed with distilled water by high-speed centrifugation, they maintained the original morphology and high stabilities under various conditions, though deoxycholate had almost completely been removed from them. From this and other experimental results, it is concluded that P-filaments consist of flagellin.