Cell-free fusion of bacteria-containing phagosomes with endocytic compartments

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 107; no. 48; pp. 20726 - 20731
• Main Authors: Becken, Ulrike, Jeschke, Andreas, Veltman, Katharina, Haas, Albert, Jahn, Reinhard
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 30.11.2010; National Acad Sciences
• Subjects: Bacteria; Bacteria - metabolism; Bacteriology; Biochemistry; Biological Assay; Biological Sciences; Cell Compartmentation; Cell-Free System - microbiology; Cells; Cytosol; Endocytosis; Endosomes; Endosomes - metabolism; Escherichia coli; Escherichia coli - metabolism; Hot Temperature; Infections; Latex; Lysosomes; Lysosomes - metabolism; Lysosomes - microbiology; Macrophages; Membrane Fusion; Microbial Viability; Microspheres; Organelles; Oxidation; Phagosomes; Phagosomes - metabolism; Phagosomes - microbiology; Proteins; rab GTP-Binding Proteins - metabolism; Salmonella; Salmonella enterica; Salmonella enterica - metabolism; SNARE proteins; SNARE Proteins - metabolism
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1007295107

Uptake of microorganisms by professional phagocytic cells leads to formation of a new subcellular compartment, the phagosome, which matures by sequential fusion with early and late endocytic compartments, resulting in oxidative and nonoxidative killing of the enclosed microbe. Few tools are available to study membrane fusion between phagocytic and late endocytic compartments in general and with pathogen-containing phagosomes in particular. We have developed and applied a fluorescence microscopy assay to study fusion of microbe-containing phagosomes with differentaged endocytic compartments in vitro. This revealed that fusion of phagosomes containing nonpathogenic Escherichia coli with lysosomes requires Rab7 and SNARE proteins but not organelle acidification. In vitro fusion experiments with phagosomes containing pathogenic Salmonella enterica serovar Typhimurium indicated that reduced fusion of these phagosomes with early and late endocytic compartments was independent of endosome and cytosol sources and, hence, a consequence of altered phagosome quality.