title: Specific loops D, E and F of nicotinic acetylcholine receptor beta1 subunit may confer imidacloprid selectivity between Myzus persicae and its predatory enemy Pardosa pseudoannulata.
abstract: One nicotinic acetylcholine receptor non-alpha subunit was cloned from the pond wolf spider, Pardosa pseudoannulata, an important predatory enemy of some insect pests with agricultural importance, such as the green peach aphid Myzus persicae. The subunit shows high amino acid identities to insect beta1 subunits (74-78%), and was denoted as Ppbeta1. Although high identities are found between Ppbeta1 and insect beta1 subunits, amino acid differences are found within loops D, E and F, important segments contributing to ligand binding. The effects of amino acid differences within these loops were evaluated by introducing loops of insect or spider beta1 subunits into rat beta2 subunit and co-expressing with insect alpha subunit. The corresponding regions of rat beta2 chimera beta2(Mpbeta1) (beta2 with loops D, E and F from M. persicae beta1 subunit Mpbeta1) were replaced by loops D, E and F of Ppbeta1 singly or together to construct different chimeras. When these chimeras were co-expressed with insect Nlalpha1, it was found that the replacement of loops D, E and F of beta2(Mpbeta1) by that of Ppbeta1 resulted in a right-ward shift of the imidacloprid dose-response curves, reflecting increases in EC(50), compared to Nlalpha1/beta2(Mpbeta1). By contrast, the influences on ACh potency were minimal. The further study showed that R81Q, N137G and F190W differences, within loops D, E and F respectively, contributed mainly to these sensitivity changes. This study contributes to our understanding of the molecular mechanism underlying selectivity of neonicotinoids against insects over spiders.
authors.affiliation: Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Song
authors.forename: Zhiqi
authors.initials: Z
authors.lastname: You
authors.forename: Xiangmei
authors.initials: X
authors.lastname: Yao
authors.forename: Jiagao
authors.initials: J
authors.lastname: Cheng
authors.forename: Zewen
authors.initials: Z
authors.lastname: Liu
authors.forename: Kejian
authors.initials: K
authors.lastname: Lin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001042:Aphids / Q000737:chemistry / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology*; D007306:Insecticides / Q000494:pharmacology*; D008969:Molecular Sequence Data; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000494:pharmacology*; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011978:Receptors, Nicotinic / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D013112:Spiders / Q000737:chemistry / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism
chemical_list: D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D021122:Protein Subunits; D011978:Receptors, Nicotinic; C082359:imidacloprid