Publications

• Biphenyl synthase, a novel type III polyketide synthase.

  Liu B., Raeth T., Beuerle T., Beerhues L.

  Biphenyls and dibenzofurans are the phytoalexins of the Maloideae, a subfamily of the economically important Rosaceae. The carbon skeleton of the two classes of antimicrobial secondary metabolites is formed by biphenyl synthase (BIS). A cDNA encoding this key enzyme was cloned from yeast-extract-t ... >> More

  Biphenyls and dibenzofurans are the phytoalexins of the Maloideae, a subfamily of the economically important Rosaceae. The carbon skeleton of the two classes of antimicrobial secondary metabolites is formed by biphenyl synthase (BIS). A cDNA encoding this key enzyme was cloned from yeast-extract-treated cell cultures of Sorbus aucuparia. BIS is a novel type III polyketide synthase (PKS) that shares about 60% amino acid sequence identity with other members of the enzyme superfamily. Its preferred starter substrate is benzoyl-CoA that undergoes iterative condensation with three molecules of malonyl-CoA to give 3,5-dihydroxybiphenyl via intramolecular aldol condensation. BIS did not accept CoA-linked cinnamic acids such as 4-coumaroyl-CoA. This substrate, however, was the preferential starter molecule for chalcone synthase (CHS) that was also cloned from S. aucuparia cell cultures. While BIS expression was rapidly, strongly and transiently induced by yeast extract treatment, CHS expression was not. In a phylogenetic tree, BIS grouped together closely with benzophenone synthase (BPS) that also uses benzoyl-CoA as starter molecule but cyclizes the common intermediate via intramolecular Claisen condensation. The molecular characterization of BIS thus contributes to the understanding of the functional diversity and evolution of type III PKSs. << Less

  Planta 225:1495-1503(2007) [PubMed] [EuropePMC]

• Biphenyl synthase from yeast-extract-treated cell cultures of Sorbus aucuparia.

  Liu B., Beuerle T., Klundt T., Beerhues L.

  Biphenyls and dibenzofurans are the phytoalexins of the Maloideae, a subfamily of the economically important Rosaceae. The biphenyl aucuparin accumulated in Sorbus aucuparia L. cell cultures in response to yeast extract treatment. Incubation of cell-free extracts from challenged cell cultures with ... >> More

  Biphenyls and dibenzofurans are the phytoalexins of the Maloideae, a subfamily of the economically important Rosaceae. The biphenyl aucuparin accumulated in Sorbus aucuparia L. cell cultures in response to yeast extract treatment. Incubation of cell-free extracts from challenged cell cultures with benzoyl-CoA and malonyl-CoA led to the formation of 3,5-dihydroxybiphenyl. This reaction was catalysed by a novel polyketide synthase, which will be named biphenyl synthase. The most efficient starter substrate for the enzyme was benzoyl-CoA. Relatively high activity was also observed with 2-hydroxybenzoyl-CoA but, instead of the corresponding biphenyl, the derailment product 2-hydroxybenzoyltriacetic acid lactone was formed. << Less

  Planta 218:492-496(2004) [PubMed] [EuropePMC]