PDBsum entry 1mv3

Endocytosis/exocytosis

PDB id

1mv3

Contents

			Protein chain

					213 a.a. *

* Residue conservation analysis

References listed in PDB file

Key reference

Title

A structure-Based model of the c-Myc/bin1 protein interaction shows alternative splicing of bin1 and c-Myc phosphorylation are key binding determinants.

Authors

A.Pineda-Lucena, C.S.Ho, D.Y.Mao, Y.Sheng, R.C.Laister, R.Muhandiram, Y.Lu, B.T.Seet, S.Katz, T.Szyperski, L.Z.Penn, C.H.Arrowsmith.

Ref.

J Mol Biol, 2005, 351, 182-194. [DOI no: 10.1016/j.jmb.2005.05.046]

PubMed id

15992821

Abstract

The N terminus of the c-Myc oncoprotein interacts with Bin1, a ubiquitously expressed nucleocytoplasmic protein with features of a tumor suppressor. The c-Myc/Bin1 interaction is dependent on the highly conserved Myc Box 1 (MB1) sequence of c-Myc. The c-Myc/Bin1 interaction has potential regulatory significance as c-Myc-mediated transformation and apoptosis can be modulated by the expression of Bin1. Multiple splicing of the Bin1 transcript results in ubiquitous, tissue-specific and tumor-specific populations of Bin1 proteins in vivo. We report on the structural features of the interaction between c-Myc and Bin1, and describe two mechanisms by which the binding of different Bin1 isoforms to c-Myc may be regulated in cells. Our findings identify a consensus class II SH3-binding motif in c-Myc and the C-terminal SH3 domain of Bin1 as the primary structure determinants of their interaction. We present biochemical and structural evidence that tumor-specific isoforms of Bin1 are precluded from interaction with c-Myc through an intramolecular polyproline-SH3 domain interaction that inhibits the Bin1 SH3 domain from binding to c-Myc. Furthermore, c-Myc/Bin1 interaction can be inhibited by phosphorylation of c-Myc at Ser62, a functionally important residue found within the c-Myc SH3-binding motif. Our data provide a structure-based model of the c-Myc/Bin1 interaction and suggest a mode of regulation that may be important for c-Myc function as a regulator of gene transcription.



	Figure 1. Figure 1. Domain architecture of (a) c-Myc and (b) Bin1. Conserved regions of c-Myc are indicated as NTD (N-terminal domain), CTD (C-terminal domain), MB1 (Myc box 1), MB2 (Myc box 2), BR (basic region), HLH (helix-loop-helix), and LZ (leucine zipper). The Thr58 and Ser62 phosphorylation sites are indicated by P. The different Bin1 domains are indicated as BAR (Bin1/amphiphysin/RVS167), U1 (unknown-1), U2 (unknown-2), MBD (c-Myc binding domain), and SH3 (Src homology 3). The position of the original murine clone #99 is shown relative to the human Bin1 sequence (black bar). The tumor-specific exon 12A splicing event is depicted against the Bin1+13 primary structure. The SH3-binding motifs of c-Myc and Bin1 are underlined. The construct with the entire MBD domain deleted is designated as Bin1ΔMBD. The C-terminal Bin1 constructs used in this work are represented schematically as Bin1C−12A, which includes a discontinuous amino acid sequence (residues 270–303 and 347–482), encoding the MBD and SH3 domains, but lacking the 12A sequence (304–346), Bin1C+12A that includes, in addition to the MBD and SH3, the tumor-specific exon 12A sequence (270–482), Bin1CΔPxxP in which the PxxP in exon 12A has been deleted, Bin1C(SH3) that encodes only the SH3 domain (402–482) and Bin1 MBD that encodes the MBD (346–402) domain alone. Residue numbering used in this work is based on the Bin1(−10+12A) isoform (Genbank accession AAC23750.1).		Figure 5. Figure 5. Solution structures of the (a) and (b) Bin1C(SH3)/c-Myc(55-68) complex and (c) and (d) the Bin1+12A intramolecular complex. (a) An ensemble of 20 superimposed NMR-derived structures of Bin1C(SH3) bound to the synthetic peptide c-Myc(55-68) (shown in red) and (c) ensemble structures of the 213 residue Bin1C+12A intramolecular complex. For clarity, only residues 305–311 (RKGPPVP) (green) and the SH3 domain of Bin1C+12A intramolecular complex are shown. The orientation of the proline-rich peptides is different in the two structures, reflecting the difference in the locations of the positively charged residues within each peptide sequence. The locations of the n-Src, RT, and distal loops of the SH3 domain are shown in (a). (b) and (d) Molecular surface representations of the Bin1C(SH3)/c-Myc(55-68) complex and the Bin1+12A intramolecular complex with positive and negative electrostatic potential colored blue and red, respectively. The bound peptide sequences (c-Myc and +12A) are shown above. The two positively charged residues of each SH3 binding region are shown in green. The conserved c-Myc residues, Thr58 and Ser62, are shown in light blue and yellow, respectively. See the text for discussion.

PROCHECK

	Headers