Dataset Information

Interhelical loops within the bHLH domain are determinant in maintaining TWIST1-DNA complexes.

ABSTRACT: The basic helix-loop-helix (bHLH) transcription factor TWIST1 is essential to embryonic development, and hijacking of its function contributes to the development of numerous cancer types. It forms either a homodimer or a heterodimeric complex with an E2A or HAND partner. These functionally distinct complexes display sometimes antagonistic functions during development, so that alterations in the balance between them lead to pronounced morphological alterations, as observed in mice and in Saethre-Chotzen syndrome patients. We, here, describe the structures of TWIST1 bHLH-DNA complexes produced in silico through molecular dynamics simulations. We highlight the determinant role of the interhelical loops in maintaining the TWIST1-DNA complex structures and provide a structural explanation for the loss of function associated with several TWIST1 mutations/insertions observed in Saethre-Chotzen syndrome patients. An animated interactive 3D complement (I3DC) is available in Proteopedia at http://proteopedia.org/w/Journal:JBSD:27.

SUBMITTER: Bouard C

PROVIDER: S-EPMC3869052 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Interhelical loops within the bHLH domain are determinant in maintaining TWIST1-DNA complexes.

Bouard Charlotte C Terreux Raphael R Hope Jennifer J Chemelle Julie Anne JA Puisieux Alain A Ansieau Stéphane S Payen Léa L

Journal of biomolecular structure & dynamics 20130325 2

The basic helix-loop-helix (bHLH) transcription factor TWIST1 is essential to embryonic development, and hijacking of its function contributes to the development of numerous cancer types. It forms either a homodimer or a heterodimeric complex with an E2A or HAND partner. These functionally distinct complexes display sometimes antagonistic functions during development, so that alterations in the balance between them lead to pronounced morphological alterations, as observed in mice and in Saethre- ...[more]

PMID: 23527594

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Project description:In the cell, misfolded proteins are processed by molecular chaperone-mediated refolding or through ubiquitin-mediated proteosome system. Dysregulation of these mechanisms facilitates the aggregation of misfolded proteins and forms aggresomes in the juxta nuclear position of the cell which are removed by lysosome-mediated autophagy pathway in the subsequent cell division. Accumulation of misfolded proteins in the cell is hallmark of several neurological disorders and other diseases including cancer. However, the exact mechanism of aggresome formation and clearance is not thoroughly understood. Reports have shown that several proteins including p300, p53, TAU, ?-synuclein, SOD, etc. contain intrinsically disordered region (IDR) which has the tendency to form aggresome. To study the nature of aggresome formation and stability of the aggresome, we have chosen Twist1 as a model protein since it has IDR regions. Twist1 is a bHLH transcription factor which plays a major role in epithelial mesenchymal transition (EMT) and shown to interact with HAT domain of p300 and p53. In the present study, we generated several deletion mutants of human Twist1 with different fluorescent tags and delineated the regions responsible for aggresome formation. The Twist1 protein contains two NLS motifs at the N-terminal region. We showed that the deletions of regions spanning the amino acids 30-46 (Twist1?30-46) which lacks the first NLS motif form larger and intense aggregates while the deletion of residues from 47 to 100 (Twist1?47-100) which lacks the second NLS motif generates smaller and less intense aggregates in the juxta nuclear position. This suggests that both the NLS motifs are needed for the proper nuclear localization of Twist1. The aggresome formation of the Twist1 deletion mutants was confirmed by counterstaining with known aggresome markers: Vimentin, HDAC6, and gamma tubulin and further validated by MG-132 treatment. In addition, it was found that the aggresomes generated by the Twist1?30-46 construct are more stable than the aggresome produced by the Twist1?47-100 construct as well as the wild-type Twist1 protein. Taken together, our data provide an important understanding on the role of IDR regions on the formation and stability of aggresomes.

Dataset Information

Interhelical loops within the bHLH domain are determinant in maintaining TWIST1-DNA complexes.

Publications

Interhelical loops within the bHLH domain are determinant in maintaining TWIST1-DNA complexes.

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