The sarcoplasmic Ca2+-ATPase: design of a perfect chemi-osmotic pump

2010 ◽  
Vol 43 (4) ◽  
pp. 501-566 ◽  
Author(s):  
Jesper V. Møller ◽  
Claus Olesen ◽  
Anne-Marie L. Winther ◽  
Poul Nissen
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Transport Mechanism ◽  
Atp Hydrolysis ◽  
Cation Binding ◽  
Thermodynamic Efficiency ◽  
Lipid Phase ◽  
Conformational States ◽  
Sarcoplasmic Reticulum Membrane ◽  
Cytosolic Domains ◽  
P Type

AbstractThe sarcoplasmic (SERCA 1a) Ca2+-ATPase is a membrane protein abundantly present in skeletal mucles where it functions as an indispensable component of the excitation–contraction coupling, being at the expense of ATP hydrolysis involved in Ca2+/H+ exchange with a high thermodynamic efficiency across the sarcoplasmic reticulum membrane. The transporter serves as a prototype of a whole family of cation transporters, the P-type ATPases, which in addition to Ca2+ transporting proteins count Na+, K+-ATPase and H+, K+-, proton- and heavy metal transporting ATPases as prominent members. The ability in recent years to produce and analyze at atomic (2·3–3 Å) resolution 3D-crystals of Ca2+-transport intermediates of SERCA 1a has meant a breakthrough in our understanding of the structural aspects of the transport mechanism. We describe here the detailed construction of the ATPase in terms of one membraneous and three cytosolic domains held together by a central core that mediates coupling between Ca2+-transport and ATP hydrolysis. During turnover, the pump is present in two different conformational states, E1 and E2, with a preference for the binding of Ca2+ and H+, respectively. We discuss how phosphorylated and non-phosphorylated forms of these conformational states with cytosolic, occluded or luminally exposed cation-binding sites are able to convert the chemical energy derived from ATP hydrolysis into an electrochemical gradient of Ca2+ across the sarcoplasmic reticulum membrane. In conjunction with these basic reactions which serve as a structural framework for the transport function of other P-type ATPases as well, we also review the role of the lipid phase and the regulatory and thermodynamic aspects of the transport mechanism.

Role of the Sarcoplasmic Reticulum Ca2+-ATPase on Heat Production and Thermogenesis

2001 ◽  
Vol 21 (2) ◽  
pp. 113-137 ◽  
Author(s):  
Leopoldo de Meis
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Atp Hydrolysis ◽  
Surrounding Medium ◽  
Chemical Energy ◽  
The Past ◽  
Sarcoplasmic Reticulum Membrane ◽  
Membrane Bound ◽  
Hydrolysis Of ◽  
Heat Released

The sarcoplasmic reticulum of skeletal muscle retains a membrane bound Ca2+-ATPase which is able to interconvert different forms of energy. A part of the chemical energy released during ATP hydrolysis is converted into heat and in the bibliography it is assumed that the amount of heat produced during the hydrolysis of an ATP molecule is always the same, as if the energy released during ATP cleavage were divided in two non-interchangeable parts: one would be converted into heat, and the other used for Ca2+ transport. Data obtained in our laboratory during the past three years indicate that the amount of heat released during the hydrolysis of ATP may vary between 7 and 32 kcal/mol depending on whether or not a transmembrane Ca2+ gradient is formed across the sarcoplasmic reticulum membrane. Drugs such as heparin and dimethyl sulfoxide are able to modify the fraction of the chemical energy released during ATP hydrolysis which is used for Ca2+ transport and the fraction which is dissipated in the surrounding medium as heat.

Structure-function studies of the sodium pump

1999 ◽  
Vol 77 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Rhoda Blostein
Keyword(s):  
Sodium Pump ◽  
Atp Hydrolysis ◽  
Cation Binding ◽  
Structural Basis ◽  
Animal Cells ◽  
Sodium Potassium ◽  
Membrane Protein Complex ◽  
And Function ◽  
P Type ◽  
Hydrolysis Of

The Na+,K+-ATPase is an ubiquitous plasma membrane protein complex that belongs to the P-type family of ion motive ATPases. Under normal conditons, it couples the hydrolysis of one molecule of ATP to the exchange of three Na+ for two K+ ions, thus maintaining the normal gradient of these cations in animal cells. Despite decades of investigation of its structure and function, the structural basis for its cation specificity and for conformational coupling of the scalar energy of ATP hydrolysis to the vectorial movement of Na+ and K+ have remained a major unresolved issue. This paper summarizes our recent studies concerned with these issues. The findings indicate that regions(s) of the amino terminus and first cytoplasmic (M2/M3) loop act synergisticaly to affect the steady-state conformational equilibrium of the enzyme. Although carboxyl- or hydroxyl-bearing amino acids comprise the cation-binding and occlusion sites, our experiments also suggest that these interactions may be modulated by juxtapositioned cytoplasmic regions.Key words: sodium, potassium, ATPase, Na+,K+-ATPase, sodium pump.

Structural similarities of Na,K-ATPase and SERCA, the Ca2+-ATPase of the sarcoplasmic reticulum

2001 ◽  
Vol 356 (3) ◽  
pp. 685-704 ◽  
Author(s):  
Kathleen J. SWEADNER ◽  
Claudia DONNET
Keyword(s):  
Crystal Structure ◽  
Sarcoplasmic Reticulum ◽  
Binding Sites ◽  
Atp Hydrolysis ◽  
Structural Features ◽  
Cleavage Sites ◽  
Transmembrane Helices ◽  
Transmembrane Topology ◽  
Key Features ◽  
P Type

The crystal structure of SERCA1a (skeletal-muscle sarcoplasmic-reticulum/endoplasmic-reticulum Ca2+-ATPase) has recently been determined at 2.6 Å (note 1 Å = 0.1nm) resolution [Toyoshima, Nakasako, Nomura and Ogawa (2000) Nature (London) 405, 647–655]. Other P-type ATPases are thought to share key features of the ATP hydrolysis site and a central core of transmembrane helices. Outside of these most-conserved segments, structural similarities are less certain, and predicted transmembrane topology differs between subclasses. In the present review the homologous regions of several representative P-type ATPases are aligned with the SERCA sequence and mapped on to the SERCA structure for comparison. Homology between SERCA and the Na,K-ATPase is more extensive than with any other ATPase, even PMCA, the Ca2+-ATPase of plasma membrane. Structural features of the Na,K-ATPase are projected on to the Ca2+-ATPase crystal structure to assess the likelihood that they share the same fold. Homology extends through all ten transmembrane spans, and most insertions and deletions are predicted to be at the surface. The locations of specific residues are examined, such as proteolytic cleavage sites, intramolecular cross-linking sites, and the binding sites of certain other proteins. On the whole, the similarity supports a shared fold, with some particular exceptions.

scholarly journals A single K+-binding site in the crystal structure of the gastric proton pump

2019 ◽  
Author(s):  
Kenta Yamamoto ◽  
Vikas Dubey ◽  
Katsumasa Irie ◽  
Hanayo Nakanishi ◽  
Himanshu Khandelia ◽  
...  
Keyword(s):  
Binding Site ◽  
Proton Pump ◽  
Atp Hydrolysis ◽  
Energy Requirement ◽  
Cation Binding ◽  
Structural Basis ◽  
Cation Binding Site ◽  
Gastric Proton Pump ◽  
Dynamics Simulations ◽  
P Type

AbstractThe gastric proton pump (H+,K+-ATPase), a P-type ATPase responsible for gastric acidification, mediates electro-neutral exchange of H+ and K+ coupled with ATP hydrolysis, but with an as yet undetermined transport stoichiometry. Here we show crystal structures at a resolution of 2.5 Å of the pump in the E2-P transition state, in which the counter-transporting cation is occluded. We found a single K+ bound to the cation-binding site of H+,K+-ATPase, indicating an exchange of 1H+/1K+ per hydrolysis of one ATP molecule. This fulfils the energy requirement for the generation of a six pH unit gradient across the membrane. The structural basis of K+recognition is resolved, supported by molecular dynamics simulations, and this establishes how H+,K+-ATPase overcomes the energetic challenge to generate an H+ gradient of more than a million-fold – the highest cation gradient known in any mammalian tissue – across the membrane.

scholarly journals The SERCA residue Glu340 mediates interdomain communication that guides Ca2+transport

2020 ◽  
Vol 117 (49) ◽  
pp. 31114-31122
Author(s):  
Maxwell M. G. Geurts ◽  
Johannes D. Clausen ◽  
Bertrand Arnou ◽  
Cédric Montigny ◽  
Guillaume Lenoir ◽  
...  
Keyword(s):  
Atp Hydrolysis ◽  
Transmembrane Helices ◽  
Tight Coupling ◽  
Hydrogen Bonding Pattern ◽  
Plasmic Reticulum ◽  
Cytosolic Domains ◽  
Dynamics Simulations ◽  
P Type ◽  
Intramolecular Communication ◽  
Interdomain Communication

The sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) is a P-type ATPase that transports Ca2+from the cytosol into the sarco(endo)plasmic reticulum (SR/ER) lumen, driven by ATP. This primary transport activity depends on tight coupling between movements of the transmembrane helices forming the two Ca2+-binding sites and the cytosolic headpiece mediating ATP hydrolysis. We have addressed the molecular basis for this intramolecular communication by analyzing the structure and functional properties of the SERCA mutant E340A. The mutated Glu340 residue is strictly conserved among the P-type ATPase family of membrane transporters and is located at a seemingly strategic position at the interface between the phosphorylation domain and the cytosolic ends of 5 of SERCA’s 10 transmembrane helices. The mutant displays a marked slowing of the Ca2+-binding kinetics, and its crystal structure in the presence of Ca2+and ATP analog reveals a rotated headpiece, altered connectivity between the cytosolic domains, and an altered hydrogen bonding pattern around residue 340. Supported by molecular dynamics simulations, we conclude that the E340A mutation causes a stabilization of the Ca2+sites in a more occluded state, hence displaying slowed dynamics. This finding underpins a crucial role of Glu340 in interdomain communication between the headpiece and the Ca2+-binding transmembrane region.

scholarly journals The SERCA residue Glu340 mediates inter-domain communication that guides Ca2+ transport

2020 ◽  
Author(s):  
Maxwell M. G. Geurts ◽  
Johannes D. Clausen ◽  
Bertrand Arnou ◽  
Cedric Montigny ◽  
Guillaume Lenoir ◽  
...  
Keyword(s):  
Atp Hydrolysis ◽  
Transmembrane Helices ◽  
Tight Coupling ◽  
Hydrogen Bonding Pattern ◽  
Plasmic Reticulum ◽  
Cytosolic Domains ◽  
Dynamics Simulations ◽  
P Type ◽  
Intramolecular Communication

AbstractThe sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) is a P-type ATPase that transports Ca2+ from the cytosol into the SR/ER lumen, driven by ATP. This primary transport activity depends on tight coupling between movements of the transmembrane helices forming the two Ca2+ binding sites and of the cytosolic headpiece mediating ATP hydrolysis. We have addressed the molecular basis for this intramolecular communication by analyzing the structure and functional properties of the SERCA mutant E340A. The mutated Glu340 residue is strictly conserved among the P-type ATPase family of membrane transporters and is located at a seemingly strategic position at the interface between the phosphorylation domain and the cytosolic ends of five out of SERCA’s ten transmembrane helices. The mutant displays a marked slowing of the Ca2+-binding kinetics, and its crystal structure in the presence of Ca2+ and ATP analogue reveals a rotated headpiece, altered connectivity between the cytosolic domains and altered hydrogen bonding pattern around residue 340. Supported by molecular dynamics simulations, we conclude that the E340A mutation causes a stabilization of the Ca2+ sites in a more occluded state, hence displaying slowed dynamics. This finding underpins a crucial role of Glu340 in inter-domain communication between the headpiece and the Ca2+-binding transmembrane region.

Functional Significance of Quaternary Organization of the Sarcoplasmic Reticulum Ca2+-ATPase

1982 ◽  
Vol 37 (5-6) ◽  
pp. 517-521 ◽  
Author(s):  
Jesper V. Møller ◽  
Talaat S. Mahrous ◽  
Jens P. Andersen ◽  
Marc le Maire
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Protein Interactions ◽  
Atp Hydrolysis ◽  
Protein Protein Interactions ◽  
Large Excess ◽  
Normal Cycle ◽  
New Approach ◽  
Protein Protein Interaction ◽  
Sarcoplasmic Reticulum Membrane ◽  
Polypeptide Chains

Abstract There is both structural and functional evidence for protein-protein interaction between Ca2+-ATPase polypeptide chains in the sarcoplasmic reticulum membrane. Studies on detergent solubilized ATPase indicate that the monomeric form is capable of performing a normal cycle of ATP hydrolysis, but some of the modulatory effects of the substrates disappear after detergent solubilization. However, the necessity of protein-protein interactions for the Ca2+ transport function remains unclarified. A new approach is described, employing ATPase reconstituted with a large excess of phospholipid, which may help to resolve this question.

scholarly journals A single K+-binding site in the crystal structure of the gastric proton pump

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Kenta Yamamoto ◽  
Vikas Dubey ◽  
Katsumasa Irie ◽  
Hanayo Nakanishi ◽  
Himanshu Khandelia ◽  
...  
Keyword(s):  
Binding Site ◽  
Proton Pump ◽  
Atp Hydrolysis ◽  
Energy Requirement ◽  
Cation Binding ◽  
Structural Basis ◽  
Cation Binding Site ◽  
Gastric Proton Pump ◽  
Dynamics Simulations ◽  
P Type

The gastric proton pump (H+,K+-ATPase), a P-type ATPase responsible for gastric acidification, mediates electro-neutral exchange of H+ and K+ coupled with ATP hydrolysis, but with an as yet undetermined transport stoichiometry. Here we show crystal structures at a resolution of 2.5 Å of the pump in the E2-P transition state, in which the counter-transporting cation is occluded. We found a single K+ bound to the cation-binding site of the H+,K+-ATPase, indicating an exchange of 1H+/1K+ per hydrolysis of one ATP molecule. This fulfills the energy requirement for the generation of a six pH unit gradient across the membrane. The structural basis of K+ recognition is resolved and supported by molecular dynamics simulations, establishing how the H+,K+-ATPase overcomes the energetic challenge to generate an H+ gradient of more than a million-fold—one of the highest cation gradients known in mammalian tissue—across the membrane.

Structural dynamics of P-type ATPase ion pumps

2019 ◽  
Vol 47 (5) ◽  
pp. 1247-1257 ◽  
Author(s):  
Mateusz Dyla ◽  
Sara Basse Hansen ◽  
Poul Nissen ◽  
Magnus Kjaergaard
Keyword(s):  
Structural Dynamics ◽  
Single Molecule ◽  
New Technologies ◽  
Atp Hydrolysis ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Time Resolved ◽  
Dynamics Simulations ◽  
Types Of Information ◽  
P Type

Abstract P-type ATPases transport ions across biological membranes against concentration gradients and are essential for all cells. They use the energy from ATP hydrolysis to propel large intramolecular movements, which drive vectorial transport of ions. Tight coordination of the motions of the pump is required to couple the two spatially distant processes of ion binding and ATP hydrolysis. Here, we review our current understanding of the structural dynamics of P-type ATPases, focusing primarily on Ca2+ pumps. We integrate different types of information that report on structural dynamics, primarily time-resolved fluorescence experiments including single-molecule Förster resonance energy transfer and molecular dynamics simulations, and interpret them in the framework provided by the numerous crystal structures of sarco/endoplasmic reticulum Ca2+-ATPase. We discuss the challenges in characterizing the dynamics of membrane pumps, and the likely impact of new technologies on the field.

Sign in / Sign up

Export Citation Format

Share Document