Dynamin A, Myosin IB and Abp1 couple phagosome maturation to F-actin binding |
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Authors: | Gopaldass Navin Patel Devang Kratzke Ramona Dieckmann Regis Hausherr Stéphanie Hagedorn Monica Monroy Roger Krüger Julia Neuhaus Eva M Hoffmann Eik Hille Katja Kuznetsov Sergei A Soldati Thierry |
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Institution: | Départment de Biochimie, Faculté des Sciences, Université de Genève, Sciences II, 30 quai Ernest Ansermet, Geneva, Switzerland. |
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Abstract: | The role of actin, class I myosins and dynamin in endocytic uptake processes is well characterized, but their role during endo-phagosomal membrane trafficking and maturation is less clear. In Dictyostelium, knockout of myosin IB (myoB) leads to a defect in membrane protein recycling from endosomes back to the plasma membrane. Here, we show that actin plays a central role in the morphology and function of the endocytic pathway. Indeed, latrunculin B (LatB) induces endosome tubulation, a phenotype also observed in dynamin A (dymA)-null cells. Knockout of dymA impairs phagosome acidification, whereas knockout of myoB delays reneutralization, a phenotype mimicked by a low dose of LatB. As a read out for actin-dependent processes during maturation, we monitored the capacity of purified phagosomes to bind F-actin in vitro, and correlated this with the presence of actin-binding and membrane-trafficking proteins. Phagosomes isolated from myoB-null cells showed an increased binding to F-actin, especially late phagosomes. In contrast, early phagosomes from dymA-null cells showed reduced binding to F-actin while late phagosomes were unaffected. We provide evidence that Abp1 is the main F-actin-binding protein in this assay and is central for the interplay between DymA and MyoB during phagosome maturation. |
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Keywords: | actin class I myosin Dictyostelium dynamin phagocytosis phagosome maturation vacuolar ATPase |
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