Divergent evolution of flavonoid 2‐oxoglutarate‐dependent dioxygenases in parsley 1

FEBS Letters

Martens, Stefan³  Lukačin, Richard³  Britsch, Lothar¹  Matern, Ulrich³  Wellmann, Frank³  Forkmann, Gert² 

[1] Merck KgaA, Frankfurterstrasse 250, D-64271 Darmstadt, Germany;Technische Universität München, Wissenschaftszentrum für Ernährung, Landnutzung und Umwelt, Department für Pflanzenwissenschaften, Lehrstuhl für Zierpflanzenbau, Am Hochanger 4, D-85350 Freising, Germany;Institut für Pharmazeutische Biologie, Philipps-Universität Marburg, Deutschhausstrasse 17 A, D-35037 Marburg, Germany

关键词: Apiaceae;    Flavonoid biosynthesis;    2-Oxoglutarate-dependent dioxygenase;    Petroselinum crispum;    ANS;    anthocyanidin synthase;    FNS;    flavone synthase;    FHT;    flavanone 3β-hydroxylase;    FLS;    flavonol synthase;    AP;    apigenin;    DHK;    dihydrokaempferol;    KM;    kaempferol;    NAR;    naringenin;   

DOI  :  10.1016/S0014-5793(03)00479-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Flavone synthases (FNSs) catalyze the oxidation of flavanones to flavones, i.e. the formation of apigenin from (2S)-naringenin. While many plants express a microsomal-type FNS II, the soluble FNS I appears to be confined to a few species of the Apiaceae and was cloned recently from parsley plants. FNS I belongs to the Fe^II/2-oxoglutarate-dependent dioxygenases characterized by short conserved sequence elements for cofactor binding, and its evolutionary context and mode of action are under investigation. Using a homology-based reverse transcription polymerase chain reaction approach, two additional flavonoid-specific dioxygenases were cloned from immature parsley leaflets, which were identified as flavanone 3β-hydroxylase (FHT) and flavonol synthase (FLS) after expression in yeast cells. Sequence alignments revealed marginal differences among the parsley FNS I and FHT polypeptides of only 6%, while much less identity (about 29%) was observed with the parsley FLS. Analogous to FNS I, FLS oxidizes the flavonoid γ-pyrone by introducing a C2, C3 double bond, and (2R,3S)-dihydrokaempferol (cis-dihydrokaempferol) was proposed recently as the most likely intermediate in both FNS I and FLS catalysis. Incubation of either FNS I or FLS with cis-dihydrokaempferol exclusively produced kaempferol and confirmed the assumption that flavonol formation occurs via hydroxylation at C3 followed by dehydratation. However, the lack of apigenin in these incubations ruled out cis-dihydrokaempferol as a free intermediate in FNS I catalysis. Furthermore, neither (+)-trans-dihydrokaempferol nor unnatural (−)-trans-dihydrokaempferol and 2-hydroxynaringenin served as a substrate for FNS I. Overall, the data suggest that FNS I has evolved uniquely in some Apiaceae as a paraphyletic gene from FHT, irrespective of the fact that FNS I and FLS catalyze equivalent desaturation reactions.

【 授权许可】

Unknown