Trinitrophenyl derivatives bind differently from parent adenine nucleotides to Ca2+-ATPase in the absence of Ca2+

Chikashi Toyoshima, Shin Ichiro Yonekura, Junko Tsueda, Shiho Iwasawa

Research output: Contribution to journalArticle

52 Citations (Scopus)

Abstract

Trinitrophenyl derivatives of adenine nucleotides are widely used for probing ATP-binding sites. Here we describe crystal structures of Ca 2+-ATPase, a representative P-type ATPase, in the absence of Ca 2+ with bound ATP, trinitrophenyl-ATP, -ADP, and -AMP at better than 2.4-Å resolution, stabilized with thapsigargin, a potent inhibitor. These crystal structures show that the binding mode of the trinitrophenyl derivatives is distinctly different from the parent adenine nucleotides. The adenine binding pocket in the nucleotide binding domain of Ca2+-ATPase is now occupied by the trinitrophenyl group, and the side chains of two arginines sandwich the adenine ring, accounting for the much higher affinities of the trinitrophenyl derivatives. Trinitrophenyl nucleotides exhibit a pronounced fluorescence in the E2P ground state but not in the other E2 states. Crystal structures of the E2P and E2 ∼ P analogues of Ca2+-ATPase with bound trinitrophenyl-AMP show that different arrangements of the three cytoplasmic domains alter the orientation and water accessibility of the trinitrophenyl group, explaining the origin of "superfluorescence." Thus, the crystal structures demonstrate that ATP and its derivatives are highly adaptable to a wide range of site topologies stabilized by a variety of interactions.

Original languageEnglish
Pages (from-to)1833-1838
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume108
Issue number5
DOIs
Publication statusPublished - Feb 1 2011
Externally publishedYes

Keywords

  • Crystallography
  • Ion pump
  • Nucleotide derivatives

ASJC Scopus subject areas

  • General

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