Dynamin - Monique Krüger - e4b07fbe88868c13%2F %2FBDLPxtal_map_filament.png&imgrefurl=http%3A%2F%2Fwww.thelowlab.org%2Fresearch- 1%2F&h=354&w=1000&tbnid=PLAYfDD- OcUs9M%3A&docid=mv0_0jnSTC_R0M&ei=A9I3VsKZKYKhyAOltqrgAg&tbm=isch&iact=rc&uact=3&dur=12632&page=1&start=0&ndsp=15&ve d=0CD8QrQMwCmoVChMIgqfCgtTyyAIVghByCh0lmwos

Table of contents Cell / organell division Dynamin superfamily Dynamin structure Dynamin as mechanoenzymes Dynamin function Arabidopsis genome DRP 1 – DRP 5

Cell / organell division

Dynamin Superfamily composed of dynamin and dynamin related proteins (DRPs) ability to bind directly to lipids, oligomerize into spiral structure around lipid bilayers modulate lipid bilayers into narrow tubules and fragment the tubules in a GTPase- dependent manner they deform and causes fission of membranes

Dynamin structure N-terminal GTPase (binds and hydrolyses GTP) conserved middle domain (involved in oligomerization) C-terminal GTPase effector domain (GED) (regulates GTPase activity)  interaction of the three conserved domains allows the oligomerization of dynamin most dynamins contain additional domains, which may account for the great diversity of cellular activities  for instance mammalian dynamins I, II, III contain a pleckstrin homology domain (PH) and a proline-rich domain (PRD)  important for lipid bindings and movement to vesicle formation sites

Dynamin family members are mechanoenzymes capable of undergoing radical conformational change Dynamin hydrolysis and its conformational change is then somehow coupled to membrane fission or fusion Dynamin as mechanoenzymes

Functions dynamins best-defined role is its involvement in clathrin-mediated endocytosis during clathrin coated vesicle (CCV) formation in endocytosis, dynamin assembles into helical structures at the neck of clathrin-coated buds and constricts and pinches off the bud neck membrane dynamin helix undergoes a conformational change upon its hydrolysis of GTP

Dynamin function involved in diverse cellular membrane-remodeling events including vesicular transport, fissions of organelles cytokinesis required for clathrin mediated trafficking, including endocytosis promotes membrane remodeling phagocytosis trafficking to/from late endosomes and trans-Golgi membranes regulate actin assembly and organization endocytic mediated pathogen entry into human cells

Arabidopsis genome has 16 dynamin related proteins grouped into 6 subfamilies (DRP1-DRP6)

DRP1 grouped in DRP1A - E DRP1A, C and E accumulate in cell plate during cytokinesis DRP1s constrict vesicles and tubules in the cell plate DRP1A is related to the CCV formation side in endocytosis DRP1A were identified by studying rsw9, a null mutant tissue samples were chosen from seedlings (cotyledon, hypocotyl and radicle), leaves (immature and mature) and stems

DRP1 DRP1A – DRP1E DRP1A the most strongly expressed proteins in all tissues DRP1A, DRP1C and DRP1E are widely expressed

DRP1A roots have poorly organized cell files with irregular division planes roots contain incomplete cell walls incomplete cell division  lack of DRP1A disrupts cytokinesis  DRP1A seems to be involved in cytokinesis

DRP2 DRP2A and DRP2B DRP2A – involved in trans-Golgi network trafficking DRP2B seems to be associated with the plasma membrane related to the CCV formation in endocytosis

Comparing localization of DRP and Clathrin Light Chaine (CLC) DRP2B, like DRP1A, is almost entirely colocalized with clathrin at the plasma membrane comparing CLC and DRP3A were not colocalized with CLC colocalization with clathrin is not a common feature of Arabidopsis DRPs, but a specific feature of the DRP1 and DRP2 subfamilies

Comparing temporal behavior of DRP and CLC GFP-DRP2B and GFP-DRP1A fluorescence appeared and disappeared later than mKO-CLC fluorescence  DRP2B and DRP1A begin to accumulate at the vesicle formation sites of the plasma membrane after the clathrin assembly and detach from there at the same time as or immediately after the clathrin disassembly

Comparing DRP2B and DRP1A DRP2B colocalizes with DRP1A at the plasma membrane DRP2B and DRP1A assemble and disassemble together at the plasma membrane

Results DRP2B and DRP1A same localization appear and disappear shortly after CLC fluorescence assemble and disassemble together at the plasma membrane  DRP2B and DRP1A interact with each other  suggesting that they form a molecular complex on the CCV formation site

DRP3 includes DRP3A and DRP3B localized to peroxisomes and mitochondria involved in fission of organelles

DRP5B involved in division of peroxisomes and chloroplasts DRP5B is the only DRP besides DRP3A and DRP3B that is known to play a direct role in organelle division

DRP5A DRP5A is involved in cytokinesis instead of organell division signals were detected in meristematic tissues expression is limited to dividing cells

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