Figure 4: Phylogenetic analysis of P450 genes and models of metabolon organization.
From: Convergent evolution in biosynthesis of cyanogenic defence compounds in plants and insects
(a) Neighbour joining phylogenetic tree with representatives from all A. thaliana (green) and B. mori (blue) P450 groups. Ten plant genes known from the cyanogenic glucoside pathway from L. japonicus (purple), S. bicolor (black), M. esculenta (olive), T. repens (silver) and T. maritima (lime), as well as ten genes from Z. filipendulae (maroon) are included. CYP405A1 from Epiphyas postvittana (fuchsia) and CYP332s from Helicoverpa armigera (navy), Heliothis virescens (grey), Spodoptera frugiperda (teal) and Manduca sexta (aqua) are also included. • Denotes P450s known to catalyse conversion of amino acids into corresponding oximes and * denotes P450s known to catalyse metabolism of oximes. • and * represent enzymes involved in cyanogenic glucoside synthesis. •• and ** represent enzymes involved in glucosinolate production. Alignment (plant–insectP450tree.mas) used for the tree can be accessed at http://genome.ku.dk/resources/zygaena/. (b) Sequence logos of conserved regions in P450s created at http://weblogo.berkeley.edu/logo.cgi. Plant/insect P450 sequence logos were generated from 173 insect sequences from B. mori, Drosophila melanogaster, Anopheles gambiae and Musca domestica, and all A. thaliana sequences (excluding CYP79s). CYP79 sequence logos were generated from 12 CYP79s from plants (A. thaliana, L. japonicus, M. esculenta, S. bicolor, T. maritima) known to catalyse conversion of amino acids into corresponding oximes. CYP71E logos were generated from two CYP71Es (S. bicolor, M. esculenta) known to catalyse conversion of oximes into cyanohydrins. (c) The proposed plant metabolon, and the putative insect metabolon including the two P450s, the UGT and the CPR. In plants, the non-covalently bound UGT is thought to be anchored on the ER membrane via the P450s and with the catalytic domain facing the cytosol. In insects, the catalytic domain of the membrane bound UGT is possibly situated inside the ER lumen. If these models are correct, the cyanogenic glucoside would be liberated from the metabolon into the cytosol in plants and inside the ER lumen in insects.
