title: Native acridone synthases I and II from Ruta graveolens L. form homodimers.
abstract: Acridone synthase II cDNA was cloned from irradiated cell suspension cultures of Ruta graveolens L. and expressed in Escherichia coli. The translated polypeptide of Mr 42,681 revealed a high degree of similarity to heterologous chalcone and stilbene synthases (70-75%), and the sequence was 94% identical to that of acridone synthase I cloned previously from elicited Ruta cells. Highly active recombinant acridone synthases I and II were purified to apparent homogeneity by a four-step purification protocol, and the affinities to N-methylanthraniloyl-CoA and malonyl-CoA were determined. The molecular mass of acridone synthase II was estimated from size exclusion chromatography on a Fractogel EMD BioSEC (S) column at about 45 kDa, as compared to a mass of 44 +/- 3 kDa found for the acridone synthase I on Superdex 75. Nevertheless, the sedimentation analysis by ultracentrifugation revealed molecular masses of 81 +/- 4 kDa for both acridone synthases. It is proposed, therefore, that the acridone synthases of Ruta graveolens are typical homodimeric plant polyketide synthases.
authors.affiliation: Institut für Pharmazeutische Biologie, Universität Marburg, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Lukacin
authors.forename: K
authors.initials: K
authors.lastname: Springob
authors.forename: C
authors.initials: C
authors.lastname: Urbanke
authors.forename: C
authors.initials: C
authors.lastname: Ernwein
authors.forename: G
authors.initials: G
authors.lastname: Schröder
authors.forename: J
authors.initials: J
authors.lastname: Schröder
authors.forename: U
authors.initials: U
authors.lastname: Matern
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D019281:Dimerization; D007527:Isoenzymes; D008969:Molecular Sequence Data; D010944:Plants / Q000201:enzymology*; D017422:Sequence Analysis, DNA
chemical_list: D007527:Isoenzymes; D000217:Acyltransferases; C086702:acridone synthase