Download MendeleyMechanism of conditional partner selectivity in MITF/TFE family transcription factors with a conserved coiled coil stammer motif.
Pogenberg, V., Ballesteros-Alvarez, J., Schober, R., Sigvaldadottir, I., Obarska-Kosinska, A., Milewski, M., Schindl, R., Ogmundsdottir, M.H., Steingrimsson, E., Wilmanns, M.(2020) Nucleic Acids Res 48: 934-948
- PubMed: 31777941
- DOI: https://doi.org/10.1093/nar/gkz1104
- Primary Citation of Related Structures:
6FX5 - PubMed Abstract:
Interrupted dimeric coiled coil segments are found in a broad range of proteins and generally confer selective functional properties such as binding to specific ligands. However, there is only one documented case of a basic-helix-loop-helix leucine zipper transcription factor-microphthalmia-associated transcription factor (MITF)-in which an insertion of a three-residue stammer serves as a determinant of conditional partner selectivity. To unravel the molecular principles of this selectivity, we have analyzed the high-resolution structures of stammer-containing MITF and an engineered stammer-less MITF variant, which comprises an uninterrupted symmetric coiled coil. Despite this fundamental difference, both MITF structures reveal identical flanking in-phase coiled coil arrangements, gained by helical over-winding and local asymmetry in wild-type MITF across the stammer region. These conserved structural properties allow the maintenance of a proper functional readout in terms of nuclear localization and binding to specific DNA-response motifs regardless of the presence of the stammer. By contrast, MITF heterodimer formation with other bHLH-Zip transcription factors is only permissive when both factors contain either the same type of inserted stammer or no insert. Our data illustrate a unique principle of conditional partner selectivity within the wide arsenal of transcription factors with specific partner-dependent functional readouts.
Organizational Affiliation:
EMBL Hamburg c/o DESY, Notkestraße 85, 22607 Hamburg, Germany.
