A role for Arabidopsis dynamin related proteins DRP2A/B in endocytosis; DRP2 function is essential for plant growth

Abstract

Endocytosis is an essential cellular process that allows cells to internalise proteins and lipid from the plasma membrane to change its composition and sense and respond to alterations in their extracellular environment. In animal cells, the protein dynamin is involved in membrane scission during endocytosis, allowing invaginating vesicles to become internalised. Arabidopsis encodes two proteins that have all the domains essential for function in the animal dynamins, Dynamin Related Proteins 2A and 2B (DRP2A and 2B). These proteins show very high sequence identity and are both expressed throughout the plant. Single mutants exhibited no obvious phenotypes but double mutants could be recovered as gametophytes carrying mutant copies of both DRP2A and DRP2B were not transmitted to the next generation. Immunolabelling localised DRP2A/B to the tips of root hairs, a site where rapid endocytosis takes place. Constitutive expression of a GTPase defective Dominant Negative form of DRP2A/B did not allow the recovery of plants expressing this protein at a detectable level, demonstrating an interference with endogenous dynamin. Using an inducible expression system Dominant Negative protein was transiently expressed at levels several fold that of the endogenous proteins. Inducible expression of the Dominant Negative protein resulted in reduced endocytosis at the tips of root hairs, as measured by internalisation of an endocytic tracer dye, and resulted in root hairs bulging and bursting. Together these data support a role for DRP2A/B in endocytosis in Arabidopsis, and demonstrates that the function of at least one of these closely related proteins is essential for plant growth.

Arabidopsis dynamin-related proteins, DRP2A and DRP2B, function coordinately in post-Golgi trafficking

“…These findings are consistent with previous reports showing the multiple localization of DRP2 to some post-Golgi organelles including the PM [6,10], TGN [23,24], and the forming edge of the cell plate [9]. Interestingly, animal dynamin also localizes to the PM, TGN, and endosomes, and is assumed to participate in clathrin-coated vesicle formation [1].…”

“…DRP2A and DRP2B localize to the leading edge of the forming cell plate, trans-Golgi network (TGN) and the PM [7,9]. The expression of dominant-negative DRP2A and DRP2B causes defects in root hair development [10]. The drp2adrp2b double mutant shows gametophyte-lethal phenotypes [11].…”

Dynamin-related proteins in plant post-Golgi traffic

“…The phylogenetic distribution of DRP1 is wider than that of DRP2 (Hong et al, 2003a). Both proteins function in several types of post-Golgi traffic pathways: clathrin-mediated endocytosis (CME; Konopka et al, 2008; Fujimoto et al, 2010; Taylor, 2011) and cell plate formation (Hong et al, 2003b; Kang et al, 2003a; Fujimoto et al, 2008). DRP2 also participates in vacuolar trafficking (Jin et al, 2001).…”

Regulation of Cell Wall Formation by Membrane Traffic

“…Members of the DRP1 and DRP2 families function in clathrin-mediated trafficking, including CME and cell plate formation, and are therefore essential for cytokinesis and cell elongation (Kang et al, 2003;Collings et al, 2008;Konopka et al, 2008;Fujimoto et al, 2010;Taylor, 2011). DRP3A, DRP3B, and DRP5B have been involved in mitochondrial, chloroplast, and peroxisome biogenesis, and DRP5A is necessary for plant cytokinesis.…”