ABSTRACT
Insect resistance to insecticides is an increasingly serious problem, and the resistant mechanisms are complicated. The resistance research based on the chemosensory pathway is one of the hot problems at present, but the specific binding mechanism of chemosensory genes and insecticides remains elusive. The binding mechanism of AlepGOBP2 (belong to insect chemosensory gene) with two insecticides was investigated by computational and experimental approaches. Our calculation results indicated that four key residues (Phe12, Ile52, Ile94, and Phe118) could steadily interact with these two insecticides and be assigned as hotspot sites responsible for their binding affinities. The significant alkyl-π and hydrophobic interactions involved by these four hotspot residues were found to be the driving forces for their binding affinities, especially for two residues (Phe12 and Ile94) that significantly contribute to the binding of chlorpyrifos, which were also validated by our binding assay results. Furthermore, we also found that the AlepGOBP2-chlorpyrifos/phoxim complexes can be more efficiently converged in the residue-specific force field-(RSFF2C) and its higher accuracy and repeatability in protein dynamics simulation, per-residue free energy decomposition, and computational alanine scanning calculations have also been achieved in this paper. These findings provided useful insights for efficient and reliable calculation of the binding mechanism of relevant AlepGOBPs with other insecticides, facilitating to develop new and efficient insecticides targeting the key sites of AlepGOBP2.
Subject(s)
Chlorpyrifos/chemistry , Insect Proteins/chemistry , Moths/metabolism , Organothiophosphorus Compounds/chemistry , Receptors, Odorant/chemistry , Receptors, Odorant/metabolism , Animals , Chlorpyrifos/metabolism , Insect Proteins/metabolism , Molecular Dynamics Simulation , Moths/chemistry , Organothiophosphorus Compounds/metabolism , Protein BindingABSTRACT
In the present study, the complete mitogenome of Theretra japonica was sequenced and compared with other sequenced mitogenomes of Sphingidae species. The mitogenome of T. japonica, containing 37 genes (13 protein-coding genes, 22 tRNA genes, and two rRNA genes) and a region rich in adenine and thymine (AT-rich region), is a circular molecule with 15,399 base pairs (bp) in length. The order and orientation of the genes in the mitogenome are similar to those of other sequenced mitogenomes of Sphingidae species. All 13 protein-coding genes (PCGs) are initiated by ATN codons except for the cytochrome C oxidase subunit 1 gene (cox1) which is initiated by the codon CGA as observed in other lepidopteran insects. Cytochrome C oxidase subunit 2 gene (cox2) has the incomplete termination codon T and NADH dehydrogenase subunit 1 gene (nad1) terminates with TAG while the remainder terminates with TAA. Additionally, the codon distributions of the 13 PCGs revealed that Ile and Leu2 are the most frequently used codon families and codons CGG, CGC, CCG, CAG, and AGG are absent. The 431 bp AT-rich region includes the motif ATAGA followed by a 23 bp poly-T stretch, short tandem repeats (STRs) of TC and TA, two copies of a 28 bp repeat 'ATTAAATTAATAAATTAA TATATTAATA' and a poly-A element. Phylogenetic analyses within Sphingidae confirmed that T. japonica belongs to the Macroglossinae and showed that the phylogenetic relationship of T. japonica is closer to Ampelophaga rubiginosa than Daphnis nerii. Phylogenetic analyses within Theretra demonstrate that T. japonica, T. jugurtha, T. suffusa, and T. capensis are clustered into one clade.
ABSTRACT
Some pentapeptides with higher alpha-helical tendency possess typical sequence pattern, such as "+ - + + - - +", "+ - - + - - +", "+ - + - - - +", and " - + + - - - +" ( "+" = D,N,E,Q,K,R,T,C, or H; "-" = L,I,V, or A), especially symmetrical motifs (a pair of reverse sequences beside palindromic segments), such as ALALA, QQAQE/EQAQQ, and REALE/ELAER, hint that the nascent peptide can fold a certain conformation in a two-way folding fashion.
