title: Cloning, expression, and purification of glyoxysomal 3-oxoacyl-CoA thiolase from sunflower cotyledons.
abstract: The glyoxysomal beta-oxidation system in sunflower (Helianthus annuus L.) cotyledons is distinguished by the coexistence of two different thiolase isoforms, thiolase I and II. So far, this phenomenon has only been described for glyoxysomes from sunflower cotyledons. Thiolase I (acetoacetyl-CoA thiolase, EC 2.3.1.9) recognizes acetoacetyl-CoA only, while thiolase II (3-oxoacyl-CoA thiolase, EC 2.3.1.16) exhibits a more broad substrate specificity towards 3-oxoacyl-CoA esters of different chain length. Here, we report on the cloning of thiolase II from sunflower cotyledons. The known DNA sequence of Cucumis sativus 3-oxoacyl-CoA thiolase was used to generate primers for cloning the corresponding thiolase from sunflower cotyledons. RT-PCR was then used to generate an internal fragment of the sunflower thiolase gene and the termini were isolated using 5'- and 3'-RACE. Full-length cDNA was generated using RT-PCR with sunflower thiolase-specific primers flanking the coding region. The resultant gene encodes a thiolase sharing at least 80% identity with other plant thiolases at the amino acid level. The recombinant sunflower thiolase II was expressed in a bacterial system in an active form and purified to apparent homogeneity in a single step using Ni-NTA agarose chromatography. The enzyme was purified 53.4-fold and had a specific activity of 235 nkat/mg protein. Pooled fractions from the Ni-NTA column resulted in an 83% yield of active enzyme to be used for further characterization.
authors.affiliation: Cell Biology, MSB, New York University Medical Center, New York, NY 10016, USA.
authors.forename: Anke C
authors.initials: AC
authors.lastname: Schiedel
authors.forename: Silke
authors.initials: S
authors.lastname: Oeljeklaus
authors.forename: Patricia
authors.initials: P
authors.lastname: Minihan
authors.forename: James H
authors.initials: JH
authors.lastname: Dyer
mesh_terms: D000102:Acetyl-CoA C-Acyltransferase / Q000096:biosynthesis* / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D018548:Cotyledon / Q000201:enzymology / Q000648:ultrastructure; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D020676:Glyoxysomes / Q000201:enzymology*; D006368:Helianthus / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D011994:Recombinant Proteins; D000102:Acetyl-CoA C-Acyltransferase