Date of Award

1988

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Abstract

The ultrastructure of polar membrane in Campylobacter jejuni was examined and was shown to line the cytoplasmic membrane at the poles of the cell like an internal cylindrical cap. The component parts of polar membrane (stalks and knobs) were found to be consistent with previous reports of this structure, although their dimensions were smaller than those described for Ectothiorhodospira mobilis.;Polar membrane in C. jejuni was visualized on membrane vesicles. It was composed of dough-nut shaped particles 5-6 nm in diameter, arranged in an hexagonal array.;C. jejuni sheds its flagella and varying proportions of the poles of the cell, resulting in the production of minicells. The formation and nature of these minicells was studied.;Histochemical staining of whole cells of C. jejuni indicated localized Mg{dollar}\sp{lcub}2+{rcub}{dollar}-ATPase activity at the poles of the cells. Ca{dollar}\sp{lcub}2+{rcub}{dollar}-ATPase activity was randomly distributed throughout the cell.;An Mg{dollar}\sp{lcub}2+{rcub}{dollar}-ATPase was purified from C. jejuni giving a specific activity of 0.3 units/mg of protein. Electron microscopy showed dough-nut shaped particles 5-6 nm in diameter. The purified enzyme possessed a single subunit type of ca. 75,000 daltons. The enzyme was cold labile, activity was abolished by trypsin, DCCD inhibited the membrane-bound form of the enzyme, and oligomycin had no inhibitory effect. The enzyme hydrolysed ATP alone and was specifically activated by Mg{dollar}\sp{lcub}2+{rcub}{dollar}. Antibodies prepared to this enzyme bound to the polar regions of whole cells of C. jejuni as shown by protein A-colloidal gold immunoelectron microscopy. Cross reactivity studies using the Western blotting technique were also performed for comparison of the ATPase from C. jejuni with other bacteria and rat liver mitochondria.;These results along with the ATPase activity localized by histochemical staining indicate that polar membrane functions as an ATPase.

Share

COinS