Analysis of the solution structure of the homeodomain of rat thyroid transcription factor 1 by 1H-NMR spectroscopy and restrained molecular mechanics

Gennaro Esposito, Federico Fogolari, Giuseppe Damante, Silvestro Formisano, Gianluca Tell, Antonio Leonardi, Roberto Di Lauro, Paolo Viglino

Research output: Contribution to journalArticlepeer-review

Abstract

The solution structure of the rat thyroid transcription factor 1 (TTF-1) homeodomain has been elucidated by 1H-NMR and restrained modeling. The TTF-1 homeodomain folds in the same manner as classical homeodomains, with three helices, a loose loop between the first two helices, and a tight turn between helix II and helix III. The typical assembly of the hydrophobic core is maintained and N-capping motifs are identified in helix I and helix III. The N-terminal stretch of helix II exhibits some mobility, similar to the preceding loop region, which may be related to its anomalous capping. The N-terminal decapeptide and the C-terminal octapeptide of the molecule (68 residues long) are disordered. All the previous characteristics are shared by all known isolated homeodomain structures. An important difference among these structures occurs at the C-terminal extension of helix III, which is either disordered or helically folded. In the TTF-1 homeodomain, the C-terminal extension of helix III (residues 51-59) appears structured, albeit not as rigidly as the preceding portion. Analysis of the NOEs and hydrogen deuterium exchange of backbone amides provides evidence for discontinuity between the two moieties of helix III, which is introduced by a tightening or a kink of residues 51-53.

Original languageEnglish (US)
Pages (from-to)101-113
Number of pages13
JournalEuropean Journal of Biochemistry
Volume241
Issue number1
DOIs
StatePublished - 1996

Keywords

  • DNA-binding protein
  • Helix-turn-helix motif
  • Homeodomain structure
  • Protein NMR
  • Thyroid-transcription-factor-1 homeodomain

ASJC Scopus subject areas

  • Biochemistry

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