ULTRASTRUCTURE AND BIOCHEMICAL-STUDIES OF THE FLAGELLAR SHEATH OF HELICOBACTER-PYLORI

Helicobacter pylori flagellar sheaths were isolated by sucrose density -gradient centrifugation and analysed by electronmicroscopy, SDS-PAGE and gas-liquid chromatography. Electronmicroscopy of thin sections of flagella showed an internal electron-dense filament and a surrounding flagellar sheath with the typical bilayer structure of a membrane. The flagellar filaments could be disintegrated by acid treatment and the resulting isolated flagellar sheaths formed vesicles, sometimes with c haracteristic structures. Centrifugation of flagellar preparations aft er acid treatment resulted in the enrichment of flagellar sheaths in t he pellet. SDS-PAGE analysis of the pellet showed a reduction of the f lagellin band and a number of protein bands of 150,76,67,65,53,51,49,2 9.5,18,17 and 16 kDa. However, there were no major protein bands chara cteristic for the sheath. Differences between the protein profiles of Sarkosyl-insoluble membranes and flagellar sheaths appeared in the low er M(r) range of 30-14 kDa. Major fatty acids of isolated flagellar sh eaths were C 14:0, C 19:0 cyc, C 18:0, and the LPS-specific fatty acid s 3-OH C 16:0 and 3-OH C 18:0. The results demonstrate that the flagel lar sheaths of H. pylori are membranes and contain LPS and proteins.