Dataset Information

Molecular cloning and heterologous expression of a cDNA encoding berbamunine synthase, a C--O phenol-coupling cytochrome P450 from the higher plant Berberis stolonifera.

ABSTRACT: A cDNA encoding a cytochrome P450-dependent oxidase, berbamunine synthase (EC 1.1.3.34; CYP80), from cell suspension cultures of the higher plant Berberis stolonifera Koehne and Wolf (barberry) has been isolated and heterologously expressed in functional form in insect cell culture using a baculovirus-based expression system. This cytochrome P450-dependent enzyme is unusual in that it catalyzes the regio- and stereoselective formation of a C--O phenol couple in bisbenzylisoquinoline alkaloid biosynthesis without concomitant incorporation of activated oxygen into the product. Consistent with the function of an oxidase rather than a monooxygenase, an essential glycine residue in the distal helix, which forms the oxygen-binding pocket in the well-studied bacterial enzyme P-450cam, is replaced by proline at the equivalent position in berbamunine synthase. This oxidase was accumulated in an active form in insect cell microsomes and accepted electrons from the endogenous NADPH-cytochrome P450 reductase. The heterologously expressed enzyme oxidatively couples either two molecules of (R)-N-methylcoclaurine to form the (R,R) dimer guattegaumerine or one molecule each of (R)- and (S)-N-methylcoclaurine to form the (R,S) dimer berbamunine. The ratio of the two bisbenzylisoquinolines formed could be altered by reductase source or by varying the enantiomer composition of the substrates.

SUBMITTER: Kraus PF

PROVIDER: S-EPMC42425 | biostudies-other | 1995 Mar

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

Molecular cloning and heterologous expression of a cDNA encoding berbamunine synthase, a C--O phenol-coupling cytochrome P450 from the higher plant Berberis stolonifera.

Kraus P F PF Kutchan T M TM

Proceedings of the National Academy of Sciences of the United States of America 19950301 6

A cDNA encoding a cytochrome P450-dependent oxidase, berbamunine synthase (EC 1.1.3.34; CYP80), from cell suspension cultures of the higher plant Berberis stolonifera Koehne and Wolf (barberry) has been isolated and heterologously expressed in functional form in insect cell culture using a baculovirus-based expression system. This cytochrome P450-dependent enzyme is unusual in that it catalyzes the regio- and stereoselective formation of a C--O phenol couple in bisbenzylisoquinoline alkaloid bio ...[more]

PMID: 7892226

Similar Datasets

Project description:Camptothecin (CAM), a complex pentacyclic pyrroloqinoline alkaloid, is the starting material for CAM-type drugs that are well-known antitumor plant drugs. Although many chemical and biological research efforts have been performed to produce CAM, a few attempts have been made to uncover the enzymatic mechanism involved in the biosynthesis of CAM. Enzyme-catalyzed oxidoreduction reactions are ubiquitously presented in living organisms, especially in the biosynthetic pathway of most secondary metabolites such as CAM. Due to a lack of its reduction partner, most catalytic oxidation steps involved in the biosynthesis of CAM have not been established. In the present study, an NADPH-cytochrome P450 reductase (CPR) encoding gene CamCPR was cloned from Camptotheca acuminata, a CAM-producing plant. The full length of CamCPR cDNA contained an open reading frame of 2127-bp nucleotides, corresponding to 708-amino acid residues. CamCPR showed 70 ~ 85% identities to other characterized plant CPRs and it was categorized to the group II of CPRs on the basis of the results of multiple sequence alignment of the N-terminal hydrophobic regions. The intact and truncate CamCPRs with N- or C-terminal His6-tag were heterologously overexpressed in Escherichia coli. The recombinant enzymes showed NADPH-dependent reductase activity toward a chemical substrate ferricyanide and a protein substrate cytochrome c. The N-terminal His6-tagged CamCPR showed 18- ~ 30-fold reduction activity higher than the C-terminal His6-tagged CamCPR, which supported a reported conclusion, i.e., the last C-terminal tryptophan of CPRs plays an important role in the discrimination between NADPH and NADH. Co-expression of CamCPR and a P450 monooxygenase, CYP73A25, a cinnamate 4-hydroxylase from cotton, and the following catalytic formation of p-coumaric acid suggested that CamCPR transforms electrons from NADPH to the heme center of P450 to support its oxidation reaction. Quantitative real-time PCR analysis showed that CamCPR was expressed in the roots, stems, and leaves of C. acuminata seedlings. The relative transcript level of CamCPR in leaves was 2.2-fold higher than that of roots and the stems showed 1.5-fold transcript level higher than the roots. The functional characterization of CamCPR will be helpful to disclose the mysterious mechanisms of the biosynthesis of CAM. The present study established a platform to characterize the P450 enzymes involved in the growth, development, and metabolism of eukaryotic organisms.

Dataset Information

Molecular cloning and heterologous expression of a cDNA encoding berbamunine synthase, a C--O phenol-coupling cytochrome P450 from the higher plant Berberis stolonifera.

Publications

Molecular cloning and heterologous expression of a cDNA encoding berbamunine synthase, a C--O phenol-coupling cytochrome P450 from the higher plant Berberis stolonifera.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets