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Cyclopiazonic Acid Is Complexed to a Divalent Metal Ion When Bound to the Sarcoplasmic Reticulum Ca2+-ATPase

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  • Department of Physiology and Biophysics
  • Interdisciplinary Nanoscience Center
  • Department of Molecular Biology
Abstract: We have determined the structure of the sarco(endo) plasmic reticulum Ca2+-ATPase (SERCA) in an E2.P-i-like form stabilized as a complex with MgF42-, an ATP analog, adenosine 5'-(beta,gamma-methylene) triphosphate (AMPPCP), and cyclopiazonic acid (CPA). The structure determined at 2.5 angstrom resolution leads to a significantly revised model of CPA binding when compared with earlier reports. It shows that a divalent metal ion is required for CPA binding through coordination of the tetramic acid moiety at a characteristic kink of the M1 helix found in all P-type ATPase structures, which is expected to be part of the cytoplasmic cation access pathway. Our model is consistent with the biochemical data on CPA function and provides new measures in structure-based drug design targeting Ca2+-ATPases, e. g. from pathogens. We also present an extended structural basis of ATP modulation pinpointing key residues at or near the ATP binding site. A structural comparison to the Na+, K+-ATPase reveals that the Phe(93) side chain occupies the equivalent binding pocket of the CPA site in SERCA, suggesting an important role of this residue in stabilization of the potassium-occluded E2 state of Na+, K+-ATPase.
Original languageEnglish
JournalJournal of Biological Chemistry
Volume284
Issue20
Pages (from-to)13513-13518
Number of pages6
ISSN0021-9258
Publication statusPublished - 15 Jun 2009

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