title: Proof of function of a putative 3-hydroxyacyl-acyl carrier protein dehydratase from higher plants by mass spectrometry of product formation.
abstract: The predicted mature portion of a putative 3-hydroxyacyl-ACP dehydratase (DH) from Arabidopsis was linked to an N-terminal poly-histidine-tag and the fusion protein expressed in Escherichia coli. Soluble dehydratase was present on induction at 25 degrees C and pure dehydratase eluted from a nickel-affinity column in 0.2-0.5M imidazole. High concentrations of imidazole were necessary to retain enzyme solubility. The dehydratase reaction is reversible and 3-hydroxybutyryl- and 2-butenoyl-ACP substrates were prepared from E. coli apo-ACP. Analysis of these suggested contamination of apo-ACP with dehydratase and an additional reverse-phase chromatographic step was required during acyl carrier protein (ACP) preparation. Activity of purified dehydratase was demonstrated by mass spectrometry using 2-butenoyl-ACP, providing the first functional experimental evidence for plant DH gene sequences.
authors.affiliation: School of Biological and Biomedical Sciences, Science Laboratories, University of Durham, South Road, Durham DH1 3LE, UK. a.p.brown@durham.ac.uk
authors.forename: Adrian
authors.initials: A
authors.lastname: Brown
authors.forename: Val
authors.initials: V
authors.lastname: Affleck
authors.forename: Johan
authors.initials: J
authors.lastname: Kroon
authors.forename: Antoni
authors.initials: A
authors.lastname: Slabas
mesh_terms: D017360:Arabidopsis / Q000201:enzymology*; D006836:Hydro-Lyases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D013058:Mass Spectrometry
chemical_list: D006836:Hydro-Lyases; C036180:beta-hydroxyacyl-(acyl-carrier-protein)dehydrase