CYP6B1 is the major enzyme responsible for the ability of Papilio polyxenes larvae to feed on plants containing furanocoumarins, allelochemicals toxic to many organisms, including insects. Coexpression of CYP6B1 with house fly P450 reductase in baculovirus-infected sf9 cells has demonstrated that, in addition to linear and angular furanocoumarins, CYP6B1 also metabolizes compounds from other chemical groups such as furanochromones and flavonoids. Molecular modeling of this P450 coupled with site directed mutagenesis has identified specific amino acids within the B-C loop region of SRS1 that are important for defining substrate specificity. Of special interest is that changing the conserved amino acid (Ile115 ® Leu115) dramatically enhances CYP6B1¢s ability to metabolize several linear furanocoumarins. Here we demonstrate that this amino acid variation affects CYP6B1¢s catalytic capabilities by changing the enzyme¢s substrate affinity, heme spin state and interaction with P450 reductase.
Species 1: Lepidoptera Papilionidae Papilio polyxenes (Black swallowtail)
Keywords: CYP6B1, metabolism
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