Regulation of Bin1 SH3 domain binding by phosphoinositides.
Bin1/M-amphiphysin-II is an amphiphysin-II isoform highly expressed in transverse tubules of adult striated muscle and is implicated in their biogenesis. Bin1 contains a basic unique amino-acid sequence, Exon10, which interacts with certain phosphoinositides such as phosphatidylinositol-4,5-bisphosphate (PI(4,5)P(2)), to localize to membranes. Here we found that Exon10 also binds to the src homology 3 (SH3) domain of Bin1 itself, and hence blocks the binding of the SH3 domain to its canonical PxxP ligands, including dynamin. This blockage was released by addition of PI(4,5)P(2) in vitro or in cells overexpressing phosphatidylinositol 4-phosphate 5-kinase. The Exon10-binding interface of the Bin1 SH3 domain largely overlapped with its PxxP-binding interface. We also show that the PLCdelta pleckstrin homology domain, another PI(4,5)P(2)-binding module, cannot substitute for Exon10 in Bin1 function in transverse tubule formation, and suggest the importance of the dual biochemical properties of Exon10 in myogenesis. Our results exemplify a novel mechanism of SH3 domain regulation, and suggest that the SH3-mediated protein-protein interactions of Bin1 are regulated by Exon10 so that it may only occur when Bin1 localizes to certain submembrane areas.
Kojima
Chie
C
Department of Molecular Biology, Osaka Bioscience Institute, Suita, Japan.
Hashimoto
Ari
A
Yabuta
Izumi
I
Hirose
Mayumi
M
Hashimoto
Shigeru
S
Kanaho
Yasunori
Y
Sumimoto
Hideki
H
Ikegami
Takahisa
T
Sabe
Hisataka
H
D048868:Adaptor Proteins, Signal Transducing; D000256:Adenoviridae / Q000235:genetics; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002522:Chlorocebus aethiops; D034281:Dynamins / Q000037:antagonists & inhibitors; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D008024:Ligands; D008958:Models, Molecular; D024510:Muscle Development; D009154:Mutation; D019906:Nuclear Magnetic Resonance, Biomolecular; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction; D025521:Tumor Suppressor Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018909:src Homology Domains / Q000235:genetics*
D048868:Adaptor Proteins, Signal Transducing; C101410:BIN1 protein, human; D002352:Carrier Proteins; D008024:Ligands; D009687:Nuclear Proteins; D010716:Phosphatidylinositols; D020033:Protein Isoforms; D034741:RNA, Small Interfering; D025521:Tumor Suppressor Proteins; D005982:Glutathione Transferase; D017853:Phosphotransferases (Alcohol Group Acceptor); C020077:1-phosphatidylinositol-4-phosphate 5-kinase; D034281:Dynamins