Phosphatidylinositol-(4,5)-bisphosphate regulates sorting signal recognition by the clathrin-associated adaptor complex AP2.
The alpha,beta2,mu2,sigma2 heterotetrameric AP2 complex is recruited exclusively to the phosphatidylinositol-4,5-bisphosphate (PtdIns4,5P(2))-rich plasma membrane where, amongst other roles, it selects motif-containing cargo proteins for incorporation into clathrin-coated vesicles. Unphosphorylated and mu2Thr156-monophosphorylated AP2 mutated in their alphaPtdIns4,5P(2), mu2PtdIns4,5P(2), and mu2Yxxvarphi binding sites were produced, and their interactions with membranes of different phospholipid and cargo composition were measured by surface plasmon resonance. We demonstrate that recognition of Yxxvarphi and acidic dileucine motifs is dependent on corecognition with PtdIns4,5P(2), explaining the selective recruitment of AP2 to the plasma membrane. The interaction of AP2 with PtdIns4,5P(2)/Yxxvarphi-containing membranes is two step: initial recruitment via the alphaPtdIns4,5P(2) site and then stabilization through the binding of mu2Yxxvarphi and mu2PtdIns4,5P(2) sites to their ligands. The second step is facilitated by a conformational change favored by mu2Thr156 phosphorylation. The binding of AP2 to acidic-dileucine motifs occurs at a different site from Yxxvarphi binding and is not enhanced by mu2Thr156 phosphorylation.
Höning
Stefan
S
Institute for Biochemistry II, University of Göttingen, Heinrich-Düker-Weg 12, 37073 Göttingen, Germany. shoening@uni-koeln.de
Ricotta
Doris
D
Krauss
Michael
M
Späte
Kira
K
Spolaore
Barbara
B
Motley
Alison
A
Robinson
Margaret
M
Robinson
Carol
C
Haucke
Volker
V
Owen
David J
DJ
D033962:Adaptor Protein Complex 2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs; D000818:Animals; D001665:Binding Sites; D015374:Biosensing Techniques; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002966:Clathrin / Q000378:metabolism*; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D033962:Adaptor Protein Complex 2; D002966:Clathrin; D008081:Liposomes; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D021382:Protein Sorting Signals; D011994:Recombinant Proteins