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

Abstract

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.

Biphenyl Phytoalexin in Sorbus pohuashanensis Suspension Cell Induced by Yeast Extract

“…FCW ( Figure 1a) grew rapidly during days 1-5, with growth rate slowing between days 5-9, and reached a plateau between days 9-14; while DCW grew quickly during days 1-5, and slowed over the final 9 days (5)(6)(7)(8)(9)(10)(11)(12)(13)(14). DCW reached its peak (0.89 g per flask) on the 5th day after subculture, as shown in Figure 1b, then continued to decrease during the culture, and this was due to the decrease of nutrient intake in cell proliferation caused by nutrient consumption in the later period of the culture.…”

Biphenyl 4-Hydroxylases Involved in Aucuparin Biosynthesis in Rowan and Apple Are Cytochrome P450 736A Proteins

“…Which role the products of this metabolon might play in preventing an infection from spreading from cell to cell via the symplastic connections remains unknown. 3,3,3,4,29,3,5-trihydroxybiphenyl, noraucuparin, 2,4-dihydroxydibenzofuran, 2-hydroxy-4-methoxydibenzofuran, and 4-hydroxy-2-methoxydibenzofuran were synthesized as described previously (Liu et al, 2004;Hüttner et al, 2010;Chizzali et al, 2012b;Khalil et al, 2013). 2,5-Dihydroxybiphenyl, benzoic acid, 3,5-dihydroxybenzoic acid, cinnamic acid, pinosylvin, resorcinol, orcinol, and their monomethyl ethers were purchased from Sigma-Aldrich (www.sigmaaldrich.com).…”

“…Aucuparin biosynthesis is initiated by BIS (Liu et al, 2004(Liu et al, , 2007. In apple, BIS is encoded by a gene family consisting of four differentially regulated subfamilies (Chizzali et al, 2012a).…”

“…Rowan (Sorbus aucuparia) cell cultures were grown and treated with Venturia inaequalis elicitor, as described previously (Liu et al, 2004;Khalil et al, 2013). Greenhouse-grown grafted shoots of apple (Malus 3 domestica 'Golden Delicious' and 'Holsteiner Cox') were inoculated with the Erwinia amylovora strain 222 gfp (Flachowsky et al, 2008), as described previously (Chizzali et al, 2012b).…”

“…The scaffold of this compound is formed by biphenyl synthase (BIS), a type III polyketide synthase, which catalyzes the condensation of the unusual starter substrate benzoyl-CoA with three molecules of malonylCoA to yield 3,5-dihydroxybiphenyl ( Fig. 1; Liu et al, 2004Liu et al, , 2007. The benzoyl moiety of the starter substrate stems from L-Phe, whose carbon skeleton is channeled into the phytoalexin biosynthetic pathway by the action of phenylalanine ammonia lyase (PAL; Hanson and Havir, 1981).…”