title: A truncation of 2B subfamily cytochromes P450 yields increased expression levels, increased solubility, and decreased aggregation while retaining function.
abstract: The hydrophobic membrane-spanning domain in four cytochromes P450 2B was removed (Delta3-21) and several positive charges were substituted at the N-terminus to increase expression and solubility. Histidine residues were appended to the C-terminus to simplify purification. The truncated proteins were highly expressed in Escherichia coli, could be released from the membrane using high salt conditions, and were purified from this fraction to specific contents up to 19 nmol P450/mg protein using a single Ni(2+)-agarose column. Gel filtration revealed that truncated P450 2B1 forms a monodisperse solution of hexamers in the absence of detergent and >95% monomers in 0.25% sodium cholate. All truncated proteins, including human 2B6, were active with 7-ethoxy-4-trifluoromethylcoumarin, and truncated 2B1 was shown to retain the native regio- and stereospecificity of testosterone hydroxylation. These data demonstrate that modification of the N-terminus yields high levels of properly folded P450s 2B with increased solubility, which are suitable for functional and structural analysis.
authors.affiliation: Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas, 77555-1031, USA. eescott@utmb.edu
authors.forename: E E
authors.initials: EE
authors.lastname: Scott
authors.forename: M
authors.initials: M
authors.lastname: Spatzenegger
authors.forename: J R
authors.initials: JR
authors.lastname: Halpert
mesh_terms: D000595:Amino Acid Sequence / Q000502:physiology*; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D002384:Catalysis; D065702:Cytochrome P-450 CYP2B6; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004285:Dogs; D004789:Enzyme Activation / Q000502:physiology; D015870:Gene Expression; D006801:Humans; D010089:Oxidoreductases, N-Demethylating / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D011817:Rabbits; D051381:Rats; D017384:Sequence Deletion; D012995:Solubility; D013329:Structure-Activity Relationship
chemical_list: D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; C585599:CYP2B6 protein, human; D065702:Cytochrome P-450 CYP2B6; D010089:Oxidoreductases, N-Demethylating