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BIN1 Membrane Curvature Sensing and Generation Show Autoinhibition Regulated by Downstream Ligands and PI(4,5)P2

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Biochemistry

American Chemical Society

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      Abstract

      In striated muscles, invaginations from the plasma membrane, termed transverse tubules (T-tubule), function in the excitation–contraction coupling machinery. BIN1 (isoform8) plays a critical role in the biogenesis of T-tubules. BIN1 contains an N-terminal BAR domain to sense and induce membrane curvature, an isoform8-specific polybasic motif (exon10) as the phosphoinositide binding module and a C-terminal Src homology 3 (SH3) domain for the recruitment of downstream proteins such as dynamin 2. Previous studies of N-BAR domains focused on elucidating mechanisms of membrane curvature sensing and generation (MC-S&G). Less is known about how MC-S&G is regulated. We found that the SH3 domain binds to the exon10 motif more strongly compared to the proline-rich domain (PRD) of dynamin 2. Furthermore, we found that the MC-S&G ability of full-length BIN1 is inhibited on membranes lacking PI(4,5)P 2. Addition of PI(4,5)P 2 in the membrane activates BIN1 to sense and induce membrane curvature. Co-presence of the SH3 domain and exon10 motif leads to the strongest phosphoinositide-mediated control of BIN1 function. Addition of SH3 domain ligand (such as PRD peptides), as well as addition of the water-soluble PI(4,5)P 2 analogue, can both enhance the MC-S&G ability of BIN1 on membranes without PI(4,5)P 2, indicating that the key to activate BIN1 is to disrupt the exon10–SH3 interaction. The nonsense mutation K436X, found in centronuclear myopathy (CNM) patients, abolishes SH3 domain binding with either exon10 or the PRD motif, resulting in increased membrane deformation capacity. Our results suggest an autoinhibition model for BIN1 that involves a synergistic regulation by membrane composition and protein–protein interactions.

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      Most cited references 64

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            Author and article information

            Affiliations
            Department of Chemistry, School of Arts & Sciences, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
            Author notes
            Journal
            Biochemistry
            Biochemistry
            bi
            bichaw
            Biochemistry
            American Chemical Society
            0006-2960
            1520-4995
            28 October 2015
            28 October 2014
            25 November 2014
            : 53
            : 46
            : 7297-7309
            25350771 4245986 10.1021/bi501082r
            Copyright © 2014 American Chemical Society

            This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.

            Funding
            National Institutes of Health, United States
            Categories
            Article
            Custom metadata
            bi501082r
            bi-2014-01082r

            Biochemistry

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