High-level expression and characterization of a highly functional Comamonas acidovorans xanthine dehydrogenase in Pseudomonas aeruginosa.
An improved procedure is described for the high-level expression of Comamonas acidovorans XDH in Pseudomonas aeruginosa PAO1-LAC. The level of functional expression (56 mg protein/L culture) is found to be 7-fold higher than that observed in Escherichia coli and 30-fold higher than that induced in C. acidovorans. Co-expression of the xdhC gene is required for maximal level of functional expression. Comparison of purified preparations of XDH expressed in the absence of xdhC (XDH(AB)) with that expressed in its presence (XDH(ABC)) shows the increased level of activity due to the level of Mo incorporation. The Fe and FAD contents of expressed enzymes are independent of xdhC co-expression. Electron paramagnetic resonance spectroscopy, circular dichroism spectroscopy, metal analysis, and kinetic properties of recombinant purified XDH(ABC) are identical with those exhibited by the native enzyme. This expression system should serve as a valuable tool for further biophysical and mechanistic investigations of xanthine dehydrogenase by site-directed mutagenesis. A method is also described to evaluate the suitability of P. aeruginosa and other organisms as potential expression hosts for five different sources of xdh genes.
Department of Chemistry, Atlanta, GA 30322, USA.
Nikolai V
NV
Ivanov
Manuela
M
Trani
Dale E
DE
Edmondson
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002942:Circular Dichroism; D020605:Delftia acidovorans / Q000201:enzymology*; D004578:Electron Spin Resonance Spectroscopy; D005822:Genetic Vectors; D006801:Humans; D008969:Molecular Sequence Data; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013057:Spectrum Analysis; D014968:Xanthine Dehydrogenase / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
D001426:Bacterial Proteins; D011994:Recombinant Proteins; D014968:Xanthine Dehydrogenase