Phagosomal Proteins of Dictyostelium discoideum |
| |
Authors: | BETSY L REZABEK JUAN M RODRIGUEZ-PARIS JAMES A CARDELLI CATHERINE P CHIA |
| |
Institution: | School of Biological Sciences, 348 Manter Hall, Box 880118, University of Nebraska, Lincoln, Nebraska 68588-0118, USA;Department of Microbiology and Immunology, Louisiana State University Medical Center, Shreveport, Louisiana 71130, USA |
| |
Abstract: | ABSTRACT. In recognizing food particles, Dictyostelium cell-surface molecules initiate cytoskeletal rearrangements that result in phagosome formation. After feeding D. discoideum cells latex beads, early phagosomes were isolated on sucrose step gradietns. Protein analyses of these vesicles showed that they contained glycoproteins and surface-labeled species corresponding to integral plasma membrane proteins. Cytoskeletal proteins also were associated with phagosomes, including myosin II, actin and a 30 kDa-actin bundling protein. As seen by the acridine orange fluorescence of vesicles containing bacteria, phagosomes were acidified rapidly by a vacuolar H+-ATPase that was detected by immunoblotting. Except for the loss of cytoskeletal proteins, few other changes over time were noted in the protein profiles of phagosomes, suggesting that phagosome maturation was incomplete. The indigestibility of the beads possibly inhibited further endocytic processing, which has been observed by others. Since nascent phagosomes contained molecules of both the cytoskeleton and plasma membrane, they will be useful in studies aimed at identifying specific protein associations occurring between membrane proteins and the cytoskeleton during phagocytosis. |
| |
Keywords: | Actin cytoskeleton phagocytosis vacuolar H*-ATPase |
|
|