Amino acid residues of both the extracellular and transmembrane domains influence binding of the antiparasitic agent milbemycin to Haemonchus contortus AVR-14B glutamate-gated chloride channels

作者：Yamaguchi Mao; Sawa Yoshihiro; Matsuda Kazuhiko; Ozoe Fumiyo; Ozoe Yoshihisa^*

来源：Biochemical and Biophysical Research Communications, 2012, 419(3): 562-566.

DOI：10.1016/j.bbrc.2012.02.062

• Milbemycin
• Glutamate-gated chloride channels
• Haemonchus contortus
• AVR-14B

Glutamate-gated chloride (GluCl) channels are pentameric receptors for the inhibitory neurotransmitter glutamate in invertebrates and are a major target for macrolide anthelmintics. Three amino acids in GluCl channels are reported to render macrolide resistance in nematodes and insects. To examine whether these three amino acids are involved in binding of the antiparasitic agent milbemycin (MLM) to the GluCl channels of the nematode parasite Haemonchus contortus, the equivalent amino acids (L256, P316, and G329) of the Hco-AVR-14B subunit were substituted with various amino acids. cDNAs encoding the wild type and mutants of this subunit were transfected into COS-1 cells for transient expression and analysis of GluCl channels. The abilities of these mutant channels to bind [H-3]MLM A(4) were remarkably decreased when compared with the wild-type channel. In patch clamp analysis, L256F and P3165 mutant channels were 37- and 100-fold less sensitive to MLM A(4) when compared with the wild-type channel, respectively. These findings indicate that amino acid changes in the beta 10 strand, the M2-M3 linker, and the M3 region influence MLM A(4) binding to the channel. Homology modeling and ligand docking studies suggest the presence of two potential binding sites for MLM A(4).

• 出版日期2012-3-16