Entamoeba histolytica: FYVE-finger domains, phosphatidylinositol 3-phosphate biosensors, associate with phagosomes but not fluid filled endosomes.
Endocytosis is an important virulence function for Entamoeba histolytica, the causative agent of amoebic dysentery. Although a number of E. histolytica proteins that regulate this process have been identified, less is known about the role of lipids. In other systems, phosphatidylinositol 3-phosphate (PI3P), a product of phosphatidylinositol 3-kinase (PI 3-kinase), has been shown to be required for endocytosis. FYVE-finger domains are protein motifs that bind specifically to PI3P. Using a PI3P biosensor consisting of glutathione-S-transferase (GST) fused to two tandem FYVE-finger domains, we have localized PI3P to phagosomes but not fluid-phase pinosomes in E. histolytica, suggesting a role for PI3P in phagocytosis. Treatment of cells with PI 3-kinase inhibitors impaired GST-2 x FYVE-phagosome association supporting the authenticity of the biosensor staining. However, treatment with PI 3-kinase inhibitors did not inhibit E. histolytica-particle interaction, indicating that PI3P is not required for the initial step, but is required for subsequent steps of phagocytosis.
Powell
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RR
Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA.
Welter
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BH
Hwu
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Bowersox
B
B
Attaway
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C
Temesvari
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LA
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D015153:Blotting, Western; D002867:Chromones / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D011992:Endosomes / Q000502:physiology; D004748:Entamoeba histolytica / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004912:Erythrocytes / Q000276:immunology; D006801:Humans; D009025:Morpholines / Q000494:pharmacology; D010587:Phagocytosis / Q000187:drug effects / Q000502:physiology; D010588:Phagosomes / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D018129:Phosphatidylinositol Phosphates / Q000502:physiology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D016622:Silver Staining; D000077191:Wortmannin
D000730:Androstadienes; D002867:Chromones; D004791:Enzyme Inhibitors; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D018129:Phosphatidylinositol Phosphates; D000081082:Phosphoinositide-3 Kinase Inhibitors; D000077191:Wortmannin; C055525:phosphatidylinositol 3-phosphate; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C116930:Pikfyve protein, mouse