New crystalline ligand-binding domain of the ecdysone receptor, useful for identifying specific ligands, potentially useful as insecticides and for controlling expression of target gene

摘要

A ligand-binding domain (LBD) of the ecdysone receptor (EcR), in crystalline form, is new. Independent claims are also included for the following: (1) discovering ligands (I) of EcR, comprising: (a) computer-assisted representation of LBD; and (b) virtual screening of data banks, containing structural data of compounds, to identify structures that interact specifically with LBD; (2) discovering ligands (I) of EcR, comprising: (a) computer-assisted representation of LBD; and (b) computer-assisted modeling of compounds able to interact specifically with LBD; (3) discovering plant-protection agents (II), or effectors (III), comprising: (a) applying method (1) or (2); (b) synthesizing identified compounds; and (c) testing them for biological activity; (4) (II) and (III) identified by method (3); (5) generating protein models of EcR LBD, or of LBD from related nuclear receptors, comprising generating a three-dimensional (3D) image of a first LBD, then of an LBD that has a mutated amino acid sequence; and (6) generating protein models of an EcR ligand binding pocket, or pocket from related receptor, by computer-assisted representation of first the 3D structure for LBD and then of a pocket having the amino acids of a selected organism or other nuclear receptor. ACTIVITY : Insecticide. The agonistic EcR ligand N-(3-methoxy-2-methylbenzoyl)-N'-(2-methoxynicotinoyl)-N'-tert-butyl-hydrazine, identified by modeling to the 3D structure of LBD, was tested against larvae of Spodoptera frugiperda on maize leaf disks. After 7 days exposure to a concentration of 4 parts per million (ppm) of the ligand, all larvae had been killed and mortality was 25 % at ligand concentration 0.8 ppm. MECHANISM OF ACTION : Insecticides identified using LBD modulate development of invertebrates regulated by the ecdysone/juvenile hormone system.