TY - JOUR T1 - A cytochrome P450 from juvenile mustard leaf beetles hydroxylates geraniol, a key step in iridoid biosynthesis JF - bioRxiv DO - 10.1101/634485 SP - 634485 AU - Nanxia Fu AU - Zhi-ling Yang AU - Yannick Pauchet AU - Christian Paetz AU - Wolfgang Brandt AU - Wilhelm Boland AU - Antje Burse Y1 - 2019/01/01 UR - http://biorxiv.org/content/early/2019/05/10/634485.abstract N2 - Juveniles of the leaf beetle Phaedon cochleariae synthesize iridoid via the mevalonate pathway to repel predators. The normal terpenoid biosynthesis is integrated into the dedicated defensive pathway by the ω-hydroxylation of geraniol to 8-hydroxygeraniol. Here we identify and characterize the geraniol 8-hydroxylase as a P450 monooxygenase using integrated transcriptomic and proteomic analyses. In the fat body, 73 individual cytochrome P450s were identified. The double stranded RNA (dsRNA)-mediated knock down of CYP6BH5 led to a significant reduction of 8-hydroxygeraniol-glucoside in the hemolymph and, later, of the chrysomelidial in the defensive secretion. Heterologously expressed CYP6BH5 converted geraniol to 8-hydroxygeraniol. In addition to geraniol, CYP6BH5 also catalyzes other monoterpenols, such as nerol and citronellol, into the corresponding α, ω-dihydroxy compounds.HighlightsThe geraniol 8-hydroxylase in Phaedon cochleariae was identified as a cytochrome P450 CYP6BH5.RNA interference emphasized the importance of CYP6BH5 in iridoid biosynthesis.In vitro enzyme assays showed that recombinant CYP6BH5 is a substrate promiscuous enzyme, converting the ω-hydroxylation of geraniol, nerol, citronellol but not linalool.Homology modeling suggested the -OH group of the substrate plays an important role in coordinating the substrates with the enzyme’s catalytic cavity. ER -