The stimulatory action of amphiphysin on dynamin function is dependent on lipid bilayer curvature.
Amphiphysin is a major dynamin-binding partner at the synapse; however, its function in fission is unclear. Incubation of large unilamellar liposomes with mice brain cytosol led to massive formation of small vesicles, whereas cytosol of amphiphysin 1 knockout mice was much less efficient in this reaction. Vesicle formation from large liposomes by purified dynamin was also strongly enhanced by amphiphysin. In the presence of liposomes, amphiphysin strongly affected dynamin GTPase activity and the recruitment of dynamin to the liposomes, but this activity was highly dependent on liposome size. Deletion from amphiphysin of its central proline-rich stretch dramatically potentiated its effect on dynamin, possibly by relieving an inhibitory intramolecular interaction. These results suggest a model in which maturation of endocytic pits correlates with the oligomerization of dynamin with either amphiphysin or other proteins with similar domain structure. Formation of these complexes is coupled to the activation of dynamin GTPase activity, thus explaining how deep invagination of the pit leads to fission.
Department of Neuroscience, Okayama University Graduate School of Medicine and Dentistry, Shikata-cho, Japan.
Yumi
Y
Yoshida
Masahiro
M
Kinuta
Tadashi
T
Abe
Shuang
S
Liang
Kenta
K
Araki
Ottavio
O
Cremona
Gilbert
G
Di Paolo
Yoshinori
Y
Moriyama
Tatsuji
T
Yasuda
Pietro
P
De Camilli
Kohji
K
Takei
D000818:Animals; D001921:Brain / Q000378:metabolism; D002417:Cattle; D022163:Clathrin-Coated Vesicles / Q000737:chemistry / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D034281:Dynamins / Q000737:chemistry / Q000378:metabolism*; D004705:Endocytosis; D066298:In Vitro Techniques; D008051:Lipid Bilayers / Q000737:chemistry; D008081:Liposomes; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D010316:Particle Size; D017434:Protein Structure, Tertiary
D008051:Lipid Bilayers; D008081:Liposomes; D009419:Nerve Tissue Proteins; C075637:amphiphysin; D034281:Dynamins