Coordinated Ras and Rac Activity Shapes Macropinocytic Cups and Enables Phagocytosis of Geometrically Diverse Bacteria

Article Article scientifique Article Coordinated Ras and Rac Activity Shapes Macropinocytic Cups and Enables Phagocytosis of Geometrically Diverse Bacteria eng 2020 author Buckley Catherine Mary 844865 author Pots Henderikus author Gueho Aurélie 655626 author Vines James H. author Munn Christopher J. author Phillips Ben A. author Gilsbach Bernd author Traynor David author Nikolaev Anton author Soldati Thierry 0000-0002-2056-7931 135632 author Parnell Andrew J. author Kortholt Arjan author King Jason S. 2912-2926 10.1016/j.cub.2020.05.049 0960-9822 https://linkinghub.elsevier.com/retrieve/pii/S0960982220307363 Engulfment of extracellular material by phagocytosis or macropinocytosis depends on the ability of cells to generate specialized cup-shaped protrusions. To effectively capture and internalize their targets, these cups are organized into a ring or ruffle of actin-driven protrusion encircling a non-protrusive interior domain. These functional domains depend on the combined activities of multiple Ras and Rho family small GTPases, but how their activities are integrated and differentially regulated over space and time is unknown. Here, we show that the amoeba Dictyostelium discoideum coordinates Ras and Rac activity using the multidomain protein RGBARG (RCC1, RhoGEF, BAR, and RasGAP-containing protein). We find RGBARG uses a tripartite mechanism of Ras, Rac, and phospholipid interactions to localize at the protruding edge and interface with the interior of both macropinocytic and phagocytic cups. There, we propose RGBARG shapes the protrusion by expanding Rac activation at the rim while suppressing expansion of the active Ras interior domain. Consequently, cells lacking RGBARG form enlarged, flat interior domains unable to generate large macropinosomes. During phagocytosis, we find that disruption of RGBARG causes a geometry-specific defect in engulfing rod-shaped bacteria and ellipsoidal beads. This demonstrates the importance of coordinating small GTPase activities during engulfment of more complex shapes and thus the full physiological range of microbes, and how this is achieved in a model professional phagocyte. Macropinocytosis Phagocytosis Dictyostelium Small GTPase Ras Rac Dewey 540 39 Département de biochimie 144 false Current Biology 30 15 8358aa96-76ac-4fce-99f4-846017528a8a Article (Published version) Public Coordinate_TS_20.pdf 8742661 application/pdf openAccess Faculté des sciences / Section de chimie et biochimie / Département de biochimie

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Coordinated Ras and Rac Activity Shapes Macropinocytic Cups and Enables Phagocytosis of Geometrically Diverse Bacteria	Current Biology			2020	377	280

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Buckley, Catherine Mary