Liu, Chang-Jun , Wang, Cheng , Yu, Xiao-Hong .
Structural insight to the conserved surface binding motifs of isoflavone O-methyltransferase.
Isoflavonoids are a class of bioactive natural products with important implications for plant, animal and human health. The majority of naturally occurred isoflavonoids are O-methylated at one or more positions. Enzymatic O-methylation of isoflavonoids is catalyzed by a group of hydroxyl methyltransferase. The enzymes are structurally classified into plant type I methyltransferase family. Eight of plant type I O-methyltransferases have recently been characterized from legume model plant Medcago truncatula. As part of our efforts in exploring the structure-function of isoflavonoid O-methyltransferase members by comparative structural analysis, we determined crystal structures for one of alfalfa I7OMT ortholog, MtIOMT3, in complex with different isoflavone substrates by MAD phasing method. Unexpectedly, besides the active site binding pocket, we revealed two additional binding motifs on the surface of IOMT3 crystals that specifically accommodate either the co-crystallized isoflavone substrates or the methylated products. The structural segments of the surface binding sites are largely conserved among the isoflavonoid O-mehtyltransferases, as well as a few related flavonoid OMT members. The binding of isoflavone on the surface dominants the conformational organization of protein tertiary structures and is critical for enzyme activity. The structural and evolutionary significance of the surface binding motifs will be further discussed.
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Chang-Jun Liu's website
1 - Brookhaven National Laboratory, Biology Department, 50 Bell Avenue, Upton, NY, 11973, U.S.A
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM