Structural Analyses of Ordered and Disordered Regions in Ecdysteroid Receptor

In insects, ecdysteroids trigger larval-to-adult transition. Ecdysteroid receptor is a heterodimer composed of two nuclear receptors, the ecdysone receptor (EcR) and Ultraspiracle (Usp). Upon dimerization EcR and Usp recognize the ecdysteroid response elements (EcREs) present in promoter regions of the ecdsysteroid-responsive genes. Detailed structural analyses of EcR and Usp DNA binding domains revealed that each protein contributes in different way to EcREs binding. Plasticity and flexibility of EcR and Usp account for great adaptability of the functional receptor for binding of different ligands and EcREs. Nevertheless the functionality of the ecdysteroid receptor is a complex matter influenced by many factor such as posttranslational modifications, observed often in disordered regions. This review will focus on data, which illustrate structure-function relationship in stably folded globular domains as well as in disordered regions of EcR and Usp. The new structural information, future goals and directions for research on recently defined factors, which might alter and influence the structure-function relationship of this receptor, are also discussed.