TY  - JOUR
AU  - Jonczyk, R.
AU  - Schmidt, H.
AU  - Osterrieder, A.
AU  - Fiesselmann, A.
AU  - Schullehner, K.
AU  - Haslbeck, M.
AU  - Sicker, D.
AU  - Hofmann, D.
AU  - Yalpani, N.
AU  - Simmons, C.
AU  - Frey, M.
AU  - Gierl, A.
TI  - Elucidation of the Final Reactions of DIMBOA-Glucoside Biosysnthesis in Maize: Characterization of Bx6 and Bx71[W][OA]
JO  - Plant physiology
VL  - 146
SN  - 0032-0889
CY  - Rockville, Md.: Soc.
PB  - JSTOR
M1  - PreJuSER-62913
SP  - 1053 - 1063
PY  - 2008
N1  - Record converted from VDB: 12.11.2012
AB  - Benzoxazinoids were identified in the early 1960s as secondary metabolites of the grasses that function as natural pesticides and exhibit allelopathic properties. Benzoxazinoids are synthesized in seedlings and stored as glucosides (glcs); the main aglucone moieties are 2,4-dihydroxy-2H-1,4-benzoxazin-3(4H)-one (DIBOA) and 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA). The genes of DIBOA-glc biosynthesis have previously been isolated and the enzymatic functions characterized. Here, the enzymes for conversion of DIBOA-glc to DIMBOA-glc are identified. DIBOA-glc is the substrate of the dioxygenase BENZOXAZINLESS6 (BX6) and the produced 2,4,7-trihydroxy-2H-1,4-benzoxazin-3-(4H)-one-glc is metabolized by the methyltransferase BX7 to yield DIMBOA-glc. Both enzymes exhibit moderate K(m) values (below 0.4 mm) and k(cat) values of 2.10 s(-1) and 0.25 s(-1), respectively. Although BX6 uses a glucosylated substrate, our localization studies indicate a cytoplasmic localization of the dioxygenase. Bx6 and Bx7 are highest expressed in seedling tissue, a feature shared with the other Bx genes. At present, Bx6 and Bx7 have no close relatives among the members of their respective gene families. Bx6 and Bx7 map to the cluster of Bx genes on the short arm of chromosome 4.
KW  - Benzoxazines: metabolism
KW  - Chromosomes, Plant
KW  - Cytoplasm: enzymology
KW  - Genes, Plant
KW  - Glucosides: biosynthesis
KW  - Glucosides: metabolism
KW  - Molecular Sequence Data
KW  - Multigene Family
KW  - Phylogeny
KW  - Protein O-Methyltransferase: genetics
KW  - Protein O-Methyltransferase: metabolism
KW  - Seedling: enzymology
KW  - Zea mays: enzymology
KW  - Zea mays: genetics
KW  - 2,4-dihydroxy-1,4-benzoxazin-3-one (NLM Chemicals)
KW  - 2-O-glucopyranosyl-4-hydroxy-7-methoxy-1,4-benzoxazin-3-one (NLM Chemicals)
KW  - Benzoxazines (NLM Chemicals)
KW  - Glucosides (NLM Chemicals)
KW  - 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (NLM Chemicals)
KW  - Protein O-Methyltransferase (NLM Chemicals)
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:18192444
C2  - pmc:PMC2259038
UR  - <Go to ISI:>//WOS:000256412200031
DO  - DOI:10.1104/pp.107.111237
UR  - https://juser.fz-juelich.de/record/62913
ER  -