TY - JOUR
T1 - Quercetin-metabolizing CYP6AS enzymes of the pollinator Apis mellifera (Hymenoptera: Apidae)
AU - Mao, Wenfu
AU - Rupasinghe, Sanjeewa G.
AU - Johnson, Reed M.
AU - Zangerl, Arthur R.
AU - Schuler, Mary A.
AU - Berenbaum, May R.
N1 - Funding Information:
This work was funded by USDA NRI AG2008-3532-18831 . We thank Gene Robinson and Karen Pruiett for assistance with honey bees.
PY - 2009/12
Y1 - 2009/12
N2 - Although the honey bee (Apis mellifera) genome contains far fewer cytochrome P450 genes associated with xenobiotic metabolism than other insect genomes sequenced to date, the CYP6AS subfamily, apparently unique to hymenopterans, has undergone an expansion relative to the genome of the jewel wasp (Nasonia vitripennis). The relative dominance of this family in the honey bee genome is suggestive of a role in processing phytochemicals encountered by honey bees in their relatively unusual diet of honey (comprising concentrated processed nectar of many plant species) and bee bread (a mixture of honey and pollen from many plant species). In this study, quercetin was initially suggested as a shared substrate for CYP6AS1, CYP6AS3, and CYP6AS4, by its presence in honey, extracts of which induce transcription of these three genes, and by in silico substrate predictions based on a molecular model of CYP6AS3. Biochemical assays with heterologously expressed CYP6AS1, CYP6AS3, CYP6AS4 and CYP6AS10 enzymes subsequently confirmed their activity toward this substrate. CYP6AS1, CYP6AS3, CYP6AS4 and CYP6AS10 metabolize quercetin at rates of 0.5 ± 0.1, 0.5 ± 0.1, 0.2 ± 0.1, and 0.2 ± 0.1 pmol quercetin/ pmol P450/min, respectively. Substrate dockings and sequence alignments revealed that the positively charged amino acids His107 and Lys217 and the carbonyl group of the backbone between Leu302 and Ala303 are essential for quercetin orientation in the CYP6AS3 catalytic site and its efficient metabolism. Multiple replacements in the catalytic site of CYP6AS4 and CYP6AS10 and repositioning of the quercetin molecule likely account for the lower metabolic activities of CYP6AS4 and CYP6AS10 compared to CYP6AS1 and CYP6AS3.
AB - Although the honey bee (Apis mellifera) genome contains far fewer cytochrome P450 genes associated with xenobiotic metabolism than other insect genomes sequenced to date, the CYP6AS subfamily, apparently unique to hymenopterans, has undergone an expansion relative to the genome of the jewel wasp (Nasonia vitripennis). The relative dominance of this family in the honey bee genome is suggestive of a role in processing phytochemicals encountered by honey bees in their relatively unusual diet of honey (comprising concentrated processed nectar of many plant species) and bee bread (a mixture of honey and pollen from many plant species). In this study, quercetin was initially suggested as a shared substrate for CYP6AS1, CYP6AS3, and CYP6AS4, by its presence in honey, extracts of which induce transcription of these three genes, and by in silico substrate predictions based on a molecular model of CYP6AS3. Biochemical assays with heterologously expressed CYP6AS1, CYP6AS3, CYP6AS4 and CYP6AS10 enzymes subsequently confirmed their activity toward this substrate. CYP6AS1, CYP6AS3, CYP6AS4 and CYP6AS10 metabolize quercetin at rates of 0.5 ± 0.1, 0.5 ± 0.1, 0.2 ± 0.1, and 0.2 ± 0.1 pmol quercetin/ pmol P450/min, respectively. Substrate dockings and sequence alignments revealed that the positively charged amino acids His107 and Lys217 and the carbonyl group of the backbone between Leu302 and Ala303 are essential for quercetin orientation in the CYP6AS3 catalytic site and its efficient metabolism. Multiple replacements in the catalytic site of CYP6AS4 and CYP6AS10 and repositioning of the quercetin molecule likely account for the lower metabolic activities of CYP6AS4 and CYP6AS10 compared to CYP6AS1 and CYP6AS3.
KW - Apis mellifera
KW - CYP6AS subfamily
KW - Cytochrome P450 monooxygenase
KW - Detoxification
KW - Flavonoid metabolism
KW - Honey
KW - Pollinator
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U2 - 10.1016/j.cbpb.2009.08.008
DO - 10.1016/j.cbpb.2009.08.008
M3 - Article
C2 - 19737624
AN - SCOPUS:72649098354
SN - 1096-4959
VL - 154
SP - 427
EP - 434
JO - Comparative Biochemistry and Physiology - B Biochemistry and Molecular Biology
JF - Comparative Biochemistry and Physiology - B Biochemistry and Molecular Biology
IS - 4
ER -