title: Hydrogen-bond formation of the residue in H-loop of the nucleotide binding domain 2 with the ATP in this site and/or other residues of multidrug resistance protein MRP1 plays a crucial role during ATP-dependent solute transport.
abstract: MRP1 couples ATP binding/hydrolysis to solute transport. We have shown that ATP binding to nucleotide-binding-domain 1 (NBD1) plays a regulatory role whereas ATP hydrolysis at NBD2 plays a crucial role in ATP-dependent solute transport. However, how ATP is hydrolyzed at NBD2 is not well elucidated. To partially address this question, we have mutated the histidine residue in H-loop of MRP1 to either a residue that prevents the formation of hydrogen-bonds with ATP and other residues in MRP1 or a residue that may potentially form these hydrogen-bonds. Interestingly, substitution of H827 in NBD1 with residues that prevented formation of these hydrogen-bonds had no effect on the ATP-dependent solute transport whereas corresponding mutations in NBD2 almost abolished the ATP-dependent solute transport completely. In contrast, substitutions of H1486 in H-loop of NBD2 with residues that might potentially form these hydrogen-bonds exerted either full function or partial function, implying that hydrogen-bond formation between the residue at 1486 and the gamma-phosphate of the bound ATP and/or other residues, such as putative catalytic base E1455, together with S769, G771, T1329 and K1333, etc., holds all the components necessary for ATP binding/hydrolysis firmly so that the activated water molecule can efficiently hydrolyze the bound ATP at NBD2.
authors.affiliation: Mayo Clinic College of Medicine, Mayo Clinic Arizona, 13400 East Shea Boulevard, Scottsdale, AZ 85259, USA.
authors.forename: Runying
authors.initials: R
authors.lastname: Yang
authors.forename: Xiu-bao
authors.initials: XB
authors.lastname: Chang
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D002460:Cell Line; D006224:Cricetinae; D018432:Drug Resistance, Multiple; D006801:Humans; D006860:Hydrogen Bonding; D006868:Hydrolysis; D007668:Kidney / Q000166:cytology; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D017434:Protein Structure, Tertiary
chemical_list: D000255:Adenosine Triphosphate; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C421109:multidrug resistance-associated protein 1