Biochemical studies on cytoplasmic membranes of agrocin sensitive and resistant strains of Agrobacterium tumefaciens

Abstract

The cytoplasmic membrane of Agrobacterium tumefaciens accounted for 12-13% of the dry weight of the whole cells and was found to consist of 71% protein, 24% lipid, and 5-6% carbohydrates. The isolated cell membrane of A. tumefaciens was resolved into 15 protein bands by polyacrylamide gel electrophoresis, four of which stained for carbohydrates. The cytoplasmic membranes of the virulent agrocin-sensitive and avirulent agrocin-sensitive strains of A. tumefaciens showed only minor quantitative variation of the protein bands in gel electrophoresis. The membrane proteins of those strains were found to be antigenically identical as studied by immunodiffusion and immunoelectrophoresis and they cross-reacted with one another. The total lipid content of the membrane of the agrocin-resistant strains was higher as compared with that in the normal strain. No appreciable differences were detected in the phospholipids, neutral lipids, and fatty acids of the whole cell and of the cytolasmic membrane.