Functional analysis of mutations in expressed acetylcholinesterase that result in azinphosmethyl and carbofuran resistance in Colorado potato beetle

The functional attributes of specific point mutations, R30K, S291G, and 1392T, associated with full-length acetylcholinesterase (AChE) cDNAs of organophosphate (OP)- and carbamate-resistant Colorado potato beetles (CPB), were determined using site-directed mutagenesis and baculovirus expression. Enzymatic and inhibitory properties of altered recombinant acetylcholinesterases (rAChEs) were examined. S291G increased the hydrolysis of substrates with larger substituted alkyl groups (e.g., BTC vs ATC) and increased the inhibitory action of inhibitors with larger alkyl groups (e.g., paraoxon, DFP, and N-propyl carbofuran vs. azinphosmethyl-oxon and N-methyl carbofuran). R30K in conjunction with S291G enhanced the hydrolysis activity of larger substrates and the inhibitory action of larger inhibitors. 1392Tattenuated theeffects of S291G in that thealtered rAChE withboth S291G and 1392T elicited substrate specificity and inhibitory properties more similar to the susceptible form of AChE without mutations. (c) 2006 Elsevier Inc. All rights reserved.