Identification of a Polygonum cuspidatum three-intron gene encoding a type III polyketide synthase producing both naringenin and p-hydroxybenzalacetone.
Benzalacetone synthase (BAS) is a member of the plant-specific type III PKS superfamily that catalyzes a one-step decarboxylative condensation of 4-coumaroyl-CoA with malonyl-CoA to produce p-hydroxybenzalacetone. In our recent work (Ma et al. in Planta 229(3):457-469, 2008), a three-intron type III PKS gene (PcPKS2) was isolated from Polygonum cuspidatum Sieb. et Zucc. Phylogenetic and functional analyses revealed this recombinant PcPKS2 to be a BAS. In this study, another three-intron type III PKS gene (PcPKS1) and its corresponding cDNA were isolated from P. cuspidatum. Sequence and phylogenetic analyses demonstrated that PcPKS1 is a chalcone sythase (CHS). However, functional and enzymatic analyses showed that recombinant PcPKS1 is a bifunctional enzyme with both, CHS and BAS activity. DNA gel blot analysis indicated that there are two to four CHS copies in the P. cuspidatum genome. RNA gel blot analysis revealed that PcPKS1 is highly expressed in the rhizomes and in young leaves, but not in the roots of the plant. PcPKS1 transcripts in leaves were inducible by pathogen infection and wounding. BAS is thought to play a crucial role in the construction of the C(6)-C(4) moiety found in a variety of phenylbutanoids, yet so far phenylbutanoids have not been isolated from P. cuspidatum. However, since PcPKS1 and PcPKS2 (Ma et al. in Planta 229(3):457-469, 2008) have been identified in P. cuspidatum, it is possible that such compounds are also produced in that plant, albeit in low concentrations.
Ma
Lan-Qing
LQ
Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Nanxincun 20#, Xiangshan, Haidian District, 100093 Beijing, People's Republic of China.
Guo
Yan-Wu
YW
Gao
Dong-Yao
DY
Ma
Dong-Ming
DM
Wang
You-Nian
YN
Li
Guo-Feng
GF
Liu
Ben-Ye
BY
Wang
Hong
H
Ye
He-Chun
HC
D000096:Acetone / Q000737:chemistry / Q000378:metabolism*; D000217:Acyltransferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel; D045468:Fallopia japonica / Q000201:enzymology* / Q000235:genetics*; D044950:Flavanones / Q000096:biosynthesis* / Q000737:chemistry; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D006863:Hydrogen-Ion Concentration; D007438:Introns / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D011994:Recombinant Proteins / Q000378:metabolism; D017421:Sequence Analysis; D013379:Substrate Specificity
D018076:DNA, Complementary; D044950:Flavanones; D011994:Recombinant Proteins; D000096:Acetone; D000217:Acyltransferases; C020141:flavanone synthetase; C005273:naringenin