The Structure and Function of Ecdysone Receptors

Ecdysteroid hormone action

“…The X-ray structures of the ligand binding pockets of EcR and Usp from various species are elucidated as summarized in [34]. As shown for vertebrate nuclear receptors, the ligand binding pocket consists of 11-12 helices arranged as an anti-parallel a-helical sandwich.…”

“…This altered (agonistic) position is a stabilized salt bridge between helix 4 and helix 12, thus allowing interaction with coactivators. Whereas these general features are common to all ecdysteroid receptors analyzed so far, there is a pronounced difference in binding affinities to various ecdysteroids besides 20-OH-ecdysone in the receptors of different origin [34]. EcR is described as a ''remarkable protein which can adapt its binding pocket to very different ligand chemistries'' [34].…”

“…Whereas these general features are common to all ecdysteroid receptors analyzed so far, there is a pronounced difference in binding affinities to various ecdysteroids besides 20-OH-ecdysone in the receptors of different origin [34]. EcR is described as a ''remarkable protein which can adapt its binding pocket to very different ligand chemistries'' [34]. This is not so surprising since some insects use moulting hormones other than 20-OH-ecdysone, mainly due to the fact that different precursors are used [35].…”

Sequencing and structural homology modeling of the ecdysone receptor in two chrysopids used in biological control of pest insects

“…Tebufenozide is harmless to non-target insects, although there are no studies on molecular/structural details that would explain the reasons for this specificity. In general, tebufenozide is specific to lepidopteran insects, and the LBP is the main domain responsible for this selective toxicity (Billas et al 2009). Thus, for those nonsensitive insects such as neuropteran green lacewings Chrysoperla carnea (Cca) (Medina et al 2001;Giolo et al 2009) and C. carnea (Godoy et al 2004a;2004b;Ferreira et al 2005;Rimoldi et al 2008), it is expected that small differences in parts of the LBP, which do not interact directly with 20E, may hinder the tebufenozide binding.…”

“…The EcR is a member of the nuclear receptor superfamily, which comprises a group of receptors containing at least one of two highly conserved domains: the centrally located DNA binding domain (DBD) and the C-terminal ligand-binding domain (LBD) (Yao et al 1993;Billas et al 2009). The LBD plays a pivotal role in ligandmediated signaling; in addition to ligand recognition, the LBD contains dimerization motifs and a ligand dependent activation function, which requires the proper position of the activation helix located at the C-terminus, of the receptor (Moras and Gronemeyer 1998;Yong et al 2003).…”