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Influence of helix 12 of Ultraspiracle on Drosophila melanogaster ecdysone receptor function
Author(s) -
Tremmel Ch.,
Azoitei A.,
Schaefer M.,
Hollmann H.,
SpindlerBarth M.
Publication year - 2011
Publication title -
insect molecular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.955
H-Index - 93
eISSN - 1365-2583
pISSN - 0962-1075
DOI - 10.1111/j.1365-2583.2011.01077.x
Subject(s) - ecdysone receptor , biology , drosophila melanogaster , nuclear receptor , ecdysone , microbiology and biotechnology , helix (gastropod) , ligand (biochemistry) , ecdysteroid , gene isoform , juvenile hormone , receptor , transcription factor , genetics , biochemistry , hormone , gene , ecology , snail
Although it has no ligand, helix 12 in the ligand binding domain of Ultraspiracle (USP) is locked in an antagonistic position. To investigate whether this position is of functional importance, we enhanced the flexibility of helix 12 by mutating two amino acids (259, located in L1–3 and F491 in helix 12). Mutated USP reduces the stability of USP and all isoforms of the ecdysone receptor (EcR) and impairs nuclear localization and DNA binding of EcR/USP L259A/F491/A , resulting in lower levels of basal transcriptional activity. Although the affinity of the ligand ponasterone A to EcR/USP L259/F491 is moderately diminished, hormone‐induced stimulation of transcriptional activity is normal. Potentiation of the ecdysone response by juvenile hormone (JH) is selectively increased in mutated heterodimers with EcR‐B1, demonstrating that the antagonistic position impairs functional interaction of the EcR complex with JHIII.