Functional expression of Ips paraconfusus cytochromes P450 exhibiting conspicuous up-regulation with feeding on host phloem.

Owing to the possible roles of insect P450s in detoxification of host material, and the biosynthesis or degradation of aggregation pheromones and hormones, these enzymes are ecologically important. Several Ips paraconfusus cytochromes P450 (P450s) were up-regulated with feeding on host phloem. Beetle P450s have previously been functionally characterized via heterologous expression in baculovirus/insect cell systems. Ips paraconfusus P450s were similarly expressed as proteins, and co-expressed with a P450 reductase. Capillary electrophoresis quantified recombinant enzymes during optimization efforts, augmenting spectral measurements. Various host secondary metabolites were tested as substrates, but functions were not determined, which may mean that the enzymes are not specific to those compounds. Although these P450s were microsomal, cellular fraction evaluation revealed possible mitochondrial and cytosolic targeting and two distinct size groups. These may represent the first insect examples of chimeric P450 signaling. The utility of capillary electrophoresis to streamline expression optimization and alternative targeting are discussed. --P. ii.