Dataset Information

Computational modeling of the bHLH domain of the transcription factor TWIST1 and R118C, S144R and K145E mutants.

ABSTRACT: Human TWIST1 is a highly conserved member of the regulatory basic helix-loop-helix (bHLH) transcription factors. TWIST1 forms homo- or heterodimers with E-box proteins, such as E2A (isoforms E12 and E47), MYOD and HAND2. Haploinsufficiency germ-line mutations of the twist1 gene in humans are the main cause of Saethre-Chotzen syndrome (SCS), which is characterized by limb abnormalities and premature fusion of cranial sutures. Because of the importance of TWIST1 in the regulation of embryonic development and its relationship with SCS, along with the lack of an experimentally solved 3D structure, we performed comparative modeling for the TWIST1 bHLH region arranged into wild-type homodimers and heterodimers with E47. In addition, three mutations that promote DNA binding failure (R118C, S144R and K145E) were studied on the TWIST1 monomer. We also explored the behavior of the mutant forms in aqueous solution using molecular dynamics (MD) simulations, focusing on the structural changes of the wild-type versus mutant dimers.The solvent-accessible surface area of the homodimers was smaller on wild-type dimers, which indicates that the cleft between the monomers remained more open on the mutant homodimers. RMSD and RMSF analyses indicated that mutated dimers presented values that were higher than those for the wild-type dimers. For a more careful investigation, the monomer was subdivided into four regions: basic, helix I, loop and helix II. The basic domain presented a higher flexibility in all of the parameters that were analyzed, and the mutant dimer basic domains presented values that were higher than the wild-type dimers. The essential dynamic analysis also indicated a higher collective motion for the basic domain.Our results suggest the mutations studied turned the dimers into more unstable structures with a wider cleft, which may be a reason for the loss of DNA binding capacity observed for in vitro circumstances.

SUBMITTER: Maia AM

PROVIDER: S-EPMC3507644 | biostudies-literature | 2012 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Computational modeling of the bHLH domain of the transcription factor TWIST1 and R118C, S144R and K145E mutants.

Maia Amanda M AM da Silva João Hm JH Mencalha André L AL Caffarena Ernesto R ER Abdelhay Eliana E

BMC bioinformatics 20120728

<h4>Background</h4>Human TWIST1 is a highly conserved member of the regulatory basic helix-loop-helix (bHLH) transcription factors. TWIST1 forms homo- or heterodimers with E-box proteins, such as E2A (isoforms E12 and E47), MYOD and HAND2. Haploinsufficiency germ-line mutations of the twist1 gene in humans are the main cause of Saethre-Chotzen syndrome (SCS), which is characterized by limb abnormalities and premature fusion of cranial sutures. Because of the importance of TWIST1 in the regulatio ...[more]

PMID: 22839202

Similar Datasets

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

Computational modeling of the bHLH domain of the transcription factor TWIST1 and R118C, S144R and K145E mutants.

Publications

Computational modeling of the bHLH domain of the transcription factor TWIST1 and R118C, S144R and K145E mutants.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets