ATP binding, not hydrolysis, at the first nucleotide-binding domain of multidrug resistance-associated protein MRP1 enhances ADP·Vi trapping at the second domain

Yue xian Hou, John R. Riordan, Xiu bao Chang

Research output: Contribution to journalArticle

31 Scopus citations

Abstract

Multidrug resistance-associated protein (MRP1) transports solutes in an ATP-dependent manner by utilizing its two nonequivalent nucleotide binding domains (NBDs) to bind and hydrolyze ATP. We found that ATP binding to the first NBD of MRP1 increases binding and trapping of ADP at the second domain (Hou, Y., Cui, L., Riordan, J. R., and Chang, X. (2002) J. Biol. Chem. 277, 5110-5119). These results were interpreted as indicating that the binding of ATP at NBD1 causes a conformational change in the molecule and increases the affinity for ATP at NBD2. However, we did not distinguish between the possibilities that the enhancement of ADP trapping might be caused by either ATP binding alone or hydrolysis. We now report the following. 1) ATP has a much lesser effect at 0 °C than at 37 °C. 2) After hexokinase treatment, the nonhydrolyzable ATP analogue, adenyl 5′-(yl iminodiphosphate), does not enhance ADP trapping. 3) Another nonhydrolyzable ATP analogue, adenosine 5′-(β,γ-methylene)triphosphate, whether hexokinase-treated or not, causes a slight enhancement. 4) In contrast, the hexokinase-treated poorly hydrolyzable ATP analogue, adenosine 5′-O-(thiotriphosphate) (ATPγS), enhances ADP trapping to a similar extent as ATP under conditions in which ATPγS should not be hydrolyzed. We conclude that: 1) ATP hydrolysis is not required to enhance ADP trapping by MRP1 protein; 2) with nucleotides having appropriate structure such as ATP or ATPγS, binding alone can enhance ADP trapping by MRP1; 3) the stimulatory effect on ADP trapping is greatly diminished when the MRP1 protein is in a "frozen state" (0 °C); and 4) the steric structure of the nucleotide γ-phosphate is crucial in determining whether binding of the nucleotide to NBD1 of MRP1 protein can induce the conformational change that influences nucleotide trapping at NBD2.

Original languageEnglish (US)
Pages (from-to)3599-3605
Number of pages7
JournalJournal of Biological Chemistry
Volume278
Issue number6
DOIs
StatePublished - Feb 7 2003

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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