Cell surface protein of Pseudomonas (Hydrogenomonas) facilis

Intact cells of Pseudomonas facilis contain one major molecular weight class of protein that is exposed at the cell surface as revealed by lactoperoxidase-catalyzed iodination with (125)I. All molecular weight classes of protein in derived cell envelope preparations are apparently saturated by iodination by lactoperoxidase after prolonged sonic treatment. The molecular weight of the predominantly exposed protein in intact cells is approximately 16,000, which is the minimal molecular weight of a cell envelope protein that precipitates as a complex with phospholipid from extracts of P. facilis. The isolation of labeled phospholipoprotein (PLP) after labeling intact cells with (125)I corroborates previous experiments which suggested a surface location for the protein portion of the phospholipoprotein (P(PLP)). Solvent extraction of cells and immunological evidence, including studies with ferritin-coupled antibodies, indicate that P(PLP) is located at the cell surface and may also be within the cell envelope. These experiments suggest that P(PLP) is the major cell surface protein in P. facilis.