A bifunctional type III polyketide synthase from raspberry (Rubus idaeus L.) with both chalcone synthase and benzalacetone synthase activity

作者：Guo, Hui-Li; Yang, Ya-Dong; Ma, Ya-Di; Liu, Wen-Bin; Feng, Jing; Luo, Zai-Qi; Lu, He-Shu; Liu, Chun-Mei; Yang, Ming-Feng; Wang, You-Nian^*; Ma, Lan-Qing^*

来源：Journal of Plant Biochemistry and Biotechnology, 2017, 26(1): 80-90.

DOI：10.1007/s13562-016-0365-7

• Benzalacetone synthase (BAS)
• Chalcone synthase (CHS)
• Raspberry
• Rubus idaeus L.
• Type III polyketide synthase

Raspberry ketone accounts for the characteristic aroma of the raspberry fruit. A bifunctional enzyme with both chalcone synthase (CHS) and benzalacetone synthase (BAS) activity is thought to play a crucial role in the synthesis of p-hydroxybenzalacetone, yet the in vitro enzymatic properties and reaction products of the CHS/BAS recombinant enzyme from raspberry have not been characterized. In this work, a type III polyketide synthase (PKS) gene (RinPKS1) and its corresponding cDNA were isolated from raspberry. Sequence and phylogenetic analyses demonstrated that RinPKS1 is a CHS. However, functional and enzymatic analyses showed that recombinant RinPKS1 is a bifunctional enzyme with both CHS and BAS activity. RinPKS1 showed some interesting characteristics: (1) no traces of bis-noryangonin and 4-coumaroyltriacetic acid lactone could be detected in the enzyme reaction mixture at different pH values; and (2) recombinant RinPKS1 overexpressed in Escherichia coli effectively yielded p-hydroxybenzalacetone as a dominant product at high pH; however, it effectively yielded naringenin as a dominant product at low pH. Furthermore, 4-coumaroyl-CoA and feruloyl-CoA were the only cinnamoyl-CoA derivatives accepted as starter substrates. RinPKS1 did not accept isobutyryl-CoA, isovaleryl-CoA or acetyl-CoA as substrates.

• 出版日期2017-1
• 单位北京农学院; 北京林业大学