title: Recombinant N-terminal nucleotide-binding domain from mouse P-glycoprotein. Overexpression, purification, and role of cysteine 430.
abstract: Varying length cDNAs encoding the N-terminal nucleotide-binding domain (NBD1) from mouse mdr1 P-glyco- protein were prepared on the basis of structure predictions. Corresponding recombinant proteins were overexpressed in Escherichia coli, and the shortest one containing amino acids 395-581 exhibited the highest solubility. Insertion of an N-terminal hexahistidine tag allowed domain purification by nickel-chelate affinity chromatography. NBD1 efficiently interacted with nucleotides. Fluorescence methods showed that ATP bound at millimolar concentrations and its 2',3'-O-(2,4,6-trinitrophenyl) derivative at micromolar concentrations, while the 2'(3')-N-methylanthraniloyl derivative had intermediate affinity. Photoaffinity labeling was achieved upon irradiation with 8-azido-ATP. The domain exhibited ATPase activity with a Km for MgATP in the millimolar range, and ATP hydrolysis was competitively inhibited by micromolar 2',3'-O-(2,4,6-trinitrophenyl)-ATP. NBD1 contained a single cysteine residue, at position 430, that was derivatized with radiolabeled N-ethylmaleimide. Cysteine modification increased 6-fold the Kd for 2'(3')-N-methylanthraniloyl-ATP and prevented 8-azido-ATP photolabeling. ATPase activity was inhibited with a 5-fold increase in the Km for MgATP. The results suggest that chemical modification of Cys-430 is involved in the N-ethylmaleimide inhibition of whole P-glycoprotein by altering substrate interaction.
authors.affiliation: Laboratoire de Biochemie Structurale et Fonctionnelle, Institut de Biologie et Chimie des Protéines, Lyon, France.
authors.forename: G
authors.initials: G
authors.lastname: Dayan
authors.forename: H
authors.initials: H
authors.lastname: Baubichon-Cortay
authors.forename: J M
authors.initials: JM
authors.lastname: Jault
authors.forename: J C
authors.initials: JC
authors.lastname: Cortay
authors.forename: G
authors.initials: G
authors.lastname: Deléage
authors.forename: A
authors.initials: A
authors.lastname: Di Pietro
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D003545:Cysteine / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism*; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D010446:Peptide Fragments; D011994:Recombinant Proteins; D000255:Adenosine Triphosphate; D003545:Cysteine