Phosphoryl Transfer and Calcium Ion Occlusion in the Calcium Pump

  title={Phosphoryl Transfer and Calcium Ion Occlusion in the Calcium Pump},
  author={Thomas Lykke-M{\o}ller S{\o}rensen and Jesper Vuust M{\o}ller and Poul Nissen},
  pages={1672 - 1675}
A tight coupling between adenosine triphosphate (ATP) hydrolysis and vectorial ion transport has to be maintained by ATP-consuming ion pumps. We report two crystal structures of Ca2+-bound sarco(endo)plasmic reticulum Ca2+–adenosine triphosphatase (SERCA) at 2.6 and 2.9 angstrom resolution in complex with (i) a nonhydrolyzable ATP analog [adenosine (β–γ methylene)–triphosphate] and (ii) adenosine diphosphate plus aluminum fluoride. SERCA reacts with ATP by an associative mechanism mediated by… 
Dephosphorylation of the Calcium Pump Coupled to Counterion Occlusion
The crystal structure of rabbit sarcoplasmic reticulum Ca2+ adenosine triphosphatase in complex with aluminum fluoride is determined, which mimics the transition state of hydrolysis of the counterion-bound (protonated) phosphoenzyme.
Lumenal gating mechanism revealed in calcium pump crystal structures with phosphate analogues
These structures show that the three cytoplasmic domains rearrange to move six out of ten transmembrane helices, thereby changing the affinity of the Ca2+-binding sites and the gating of the ion pathway.
What ATP binding does to the Ca2+ pump and how nonproductive phosphoryl transfer is prevented in the absence of Ca2+
The present crystal structure explains what ATP binding itself does to SERCA and how nonproductive phosphorylation is prevented in E2 and why Ca2+ binding is absolutely necessary for phosphoryl transfer.
The Structural Basis for Coupling of Ca2+ Transport to ATP Hydrolysis by the Sarcoplasmic Reticulum Ca2+-ATPase
From these structures Ca2+-ATPase emerges as a molecular machine, where globular cytosolic domains and transmembrane helices work in concert like a mechanical pump, as can be vividly demonstrated in animated versions of the pump cycle.
Calcium Pump, Chemistry of
Methods have been established for a detailed functional analysis of mutants, allowing definition of the roles of the individual amino acid residues in the partial reaction steps, and the mutational studies can now be correlated with the positions of the residues in crystal structures of SERCA in various conformational states.
The structural basis of calcium transport by the calcium pump
Functional studies and three new crystal structures of the rabbit skeletal muscle Ca2+-ATPase are presented, representing the phosphoenzyme intermediates associated withCa2+ binding, Ca2- translocation and dephosphorylation, that are based on complexes with a functional ATP analogue, beryllium fluoride and aluminium fluoride, respectively.
Concerted conformational effects of Ca2+ and ATP are required for activation of sequential reactions in the Ca2+ ATPase (SERCA) catalytic cycle.
The influence of adenosine 5'-(beta,gamma-methylene) triphosphate, Ca2+, and Mg2+ on proteolytic digestion patterns, interpreted in the light of known crystal structures, indicates that a Ca2+-dependent conformation of the ATPase headpiece is required for a further transition induced by nucleotide binding.
Modulatory and catalytic modes of ATP binding by the calcium pump
A mechanism of Ca2+ activation of phosphorylation leading directly from the compact E2‐ATP form to the Ca2E1‐ATp state is proposed and a role of Glu439 in ATP modulation of other steps of the functional cycle is suggested.


Structural changes in the calcium pump accompanying the dissociation of calcium
The structure of the enzyme stabilized by thapsigargin, a potent inhibitor, shows large conformation differences from that in E1Ca2+.
Structure of the calcium pump from sarcoplasmic reticulum at 8-Å resolution
A distinct cavity leads to the putative calcium-binding site, providing a plausible path for calcium release to the lumen of the sarcoplasmic reticulum.
Occlusion of divalent cations in the phosphorylated calcium pump of sarcoplasmic reticulum.
  • Y. Dupont
  • Biology, Chemistry
    European journal of biochemistry
  • 1980
Experiments performed in the absence of magnesium reveal another divalent cation binding site which is probably directly involved in ATP and Pi binding and determines the stability and ADP-sensitivity of the phosphoenzyme.
A structural model for the catalytic cycle of Ca(2+)-ATPase.
It is hypothesized that both the nucleotide-binding and beta-sheet domains are highly mobile and driven by Brownian motion to elicit phosphoenzyme formation and calcium transport, respectively, and the reaction cycle of Ca(2+)-ATPase would have elements of a Brownian ratchet.
Crystal structure of the calcium pump of sarcoplasmic reticulum at 2.6 Å resolution
Comparison with a low-resolution electron density map of the enzyme in the absence of calcium and with biochemical data suggests that large domain movements take place during active transport.
Location of high affinity Ca2 +-binding sites within the predicted transmembrahe domain of the sarco-plasmic reticulum Ca2+-ATPase
Results suggest that at least six polar, oxygen-containing residues lying near the centre of the transmembrane domain provide ligands for one or both of the two high affinity Ca2+ binding sites in the Ca2-ATPase.
Ca2+ binding to occluded sites in the CrATP-ATPase complex of sarcoplasmic reticulum: evidence for two independent high-affinity sites.
It is evident that when in the occluded state, the higher affinity site is available without Ca2+ first being bound to the lower affinity site, eliminating cooperativity from the binding mechanism.
Importance of Transmembrane Segment M1 of the Sarcoplasmic Reticulum Ca2+-ATPase in Ca2+ Occlusion and Phosphoenzyme Processing*
Alanine substitution of Leu65 accelerated the transition to ADP-insensitive phosphoenzyme and blocked its dephosphorylation, thus demonstrating that this part of M1, besides being important in Ca2+ interaction, furthermore, is a critical element in the long range signaling between the transmembrane domain and the cytoplasmic catalytic site.