Structure and Mechanism of P-Type ATPase Ion Pumps

Dyla, Mateusz; Kjærgaard, Magnus; Poulsen, Hanne; Nissen, Poul

doi:10.1146/annurev-biochem-010611-112801

Cited by 128 publications

(119 citation statements)

References 126 publications

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“…P-type ATPases share a similar molecular architecture, which comprises three distinct cytosolic domains, i.e., the actuator (A), nucleotide binding (N) and phosphorylation (P) domains, and two transmembrane domains, the transport domain of six helical segments (TM1 to TM6), which contains the ion binding sites located halfway through the membrane, and a class-specific support domain of four helical segments (TM7 to TM10). Moreover, in many P-type ATPases, the N- or C-terminal extensions at the cytosolic side act as regulatory (R) domains, which are autoinhibitory or can function as sensors for the transported cations [ 3 , 4 ]. Interestingly, the R domains of P-type ATPases have the characteristics of disordered proteins and are therefore highly variable and flexible.…”

Section: Introductionmentioning

confidence: 99%

Protein Adsorption on Solid Supported Membranes: Monitoring the Transport Activity of P-Type ATPases

Tadini‐Buoninsegni

2020

Molecules

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P-type ATPases are a large family of membrane transporters that are found in all forms of life. These enzymes couple ATP hydrolysis to the transport of various ions or phospholipids across cellular membranes, thereby generating and maintaining crucial electrochemical potential gradients. P-type ATPases have been studied by a variety of methods that have provided a wealth of information about the structure, function, and regulation of this class of enzymes. Among the many techniques used to investigate P-type ATPases, the electrical method based on solid supported membranes (SSM) was employed to investigate the transport mechanism of various ion pumps. In particular, the SSM method allows the direct measurement of charge movements generated by the ATPase following adsorption of the membrane-bound enzyme on the SSM surface and chemical activation by a substrate concentration jump. This kind of measurement was useful to identify electrogenic partial reactions and localize ion translocation in the reaction cycle of the membrane transporter. In the present review, we discuss how the SSM method has contributed to investigate some key features of the transport mechanism of P-type ATPases, with a special focus on sarcoplasmic reticulum Ca2+-ATPase, mammalian Cu+-ATPases (ATP7A and ATP7B), and phospholipid flippase ATP8A2.

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Section: Introductionmentioning

confidence: 99%

Protein Adsorption on Solid Supported Membranes: Monitoring the Transport Activity of P-Type ATPases

Tadini‐Buoninsegni

2020

Molecules

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“…Ca 2+ pumping maintains SR Ca 2+ stores and is performed by the sarco/endoplasmic reticulum Ca 2+ -ATPase (SERCA). SERCA transports Ca 2+ -ions against a steep electrochemical gradient by cycling through a series of conformational states with alternating access to two Ca 2+ -binding sites in the transmembrane domain 1,2 . The ATP powered reaction cycle includes the formation and breakdown of a phosphoenzyme intermediate which is characteristic of the P-type ATPase family.…”

Section: Introductionmentioning

confidence: 99%

“…The structure and dynamics of SERCA have been described in great detail, 1,[16][17][18][19] but much less is known about HRC. Sequence analysis does not reveal any conserved domains in HRC.…”

Section: Introductionmentioning

confidence: 99%

Histidine-rich Ca²⁺-binding protein stimulates the transport cycle of SERCA through a conformation-dependent fuzzy complex

Ayeotan

Hansen

Boesen

et al. 2020

Preprint

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The histidine-rich Ca2+-binding protein (HRC) stimulates the sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) to increase Ca2+-uptake into the lumen. HRC also binds the triadin scaffold in a Ca2+-dependent manner, and HRC tunes both the uptake and release of Ca2+ depending on the concentration in the intracellular Ca2+-stores. We investigated how HRC stimulates SERCA pumping using biochemical and biophysical assays, and show that HRC is an intrinsically disordered protein that binds directly to SERCA via electrostatic interactions. The affinity of the interaction depends on the conformation of SERCA, and HRC binds most tightly in the calcium-released E2P state. This state marks the end of the rate-limiting [Ca2]E1P to E2P transition of SERCA, and suggests that HRC stimulates SERCA by preferentially stabilizing the end point of this transition. HRC remains disordered in the bound state and thus binds in a dynamic, fuzzy complex. The binding of HRC to SERCA shows that fuzzy complexes formed by disordered proteins may be conformation-specific, and use this specificity to modulate the functional cycle of complex molecular machines such as a P-type ATPase.

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“…S10, Supporting information), showed that binding of Ca 2+ to the transmembrane transport sites ( Fig. 1) decreases the amplitude of motion in the ion transport domain [29,30], namely in transmembrane helices M1, M3 and M4, as evidenced by a decrease in RMSF for this region (Fig. 1).…”

mentioning

confidence: 96%

Dynamics-driven allostery underlies pre-activation of the regulatory Ca²⁺-ATPase/phospholamban complex

Raguimova¹,

Aguayo‐Ortiz²,

Robia³

et al. 2020

Preprint

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Sarcoplasmic reticulum (SR) Ca 2+ -ATPase (SERCA) and phospholamban (PLB) are essential for intracellular Ca 2+ transport in myocytes. Ca 2+ -dependent activation of SERCA-PLB provides a rheostat function that regulates cytosolic and SR Ca 2+ levels. While experimental and computational studies alone have led to a greater insight into the mechanisms for SERCA-PLB regulation, the structural changes induced by Ca 2+ binding and how those are communicated to couple enzymatic activity with active transport remain poorly understood. Therefore, we have performed atomistic simulations totaling 32.7 μs and cell-based intramolecular fluorescence resonance energy transfer (FRET) experiments to determine structural changes of PLB-bound SERCA in response to Ca 2+ binding. Complementary simulations and experiments showed structural disorder underlies PLB inhibition of SERCA, and Ca 2+ binding is sufficient to shift the protein population toward a structurally ordered state of the complex. This structural transition results in a redistribution of structural states toward a partially closed conformation of SERCA's cytosolic headpiece. Closure is accompanied by functional interactions between the N-domain β5-β6 loop and the A-domain. Regulation of these key structural elements indicate that Ca 2+ is a critical mediator of allosteric signaling that dictates structural changes and motions that pre-activate SERCA-PLB. These findings provide direct support that dynamically driven protein allostery underlies PLB regulation of SERCA. These functional insights at unprecedented spatiotemporal resolution suggest a general modular architecture mechanism for dynamic regulation of the SERCA-PLB complex. Understanding these mechanisms is of paramount importance to guide therapeutic modulation of SERCA and other evolutionarily related ion-motive ATPases.

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Structure and Mechanism of P-Type ATPase Ion Pumps

Cited by 128 publications

References 126 publications

Protein Adsorption on Solid Supported Membranes: Monitoring the Transport Activity of P-Type ATPases

Protein Adsorption on Solid Supported Membranes: Monitoring the Transport Activity of P-Type ATPases

Histidine-rich Ca²⁺-binding protein stimulates the transport cycle of SERCA through a conformation-dependent fuzzy complex

Dynamics-driven allostery underlies pre-activation of the regulatory Ca²⁺-ATPase/phospholamban complex

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Structure and Mechanism of P-Type ATPase Ion Pumps

Cited by 128 publications

References 126 publications

Protein Adsorption on Solid Supported Membranes: Monitoring the Transport Activity of P-Type ATPases

Protein Adsorption on Solid Supported Membranes: Monitoring the Transport Activity of P-Type ATPases

Histidine-rich Ca2+-binding protein stimulates the transport cycle of SERCA through a conformation-dependent fuzzy complex

Dynamics-driven allostery underlies pre-activation of the regulatory Ca2+-ATPase/phospholamban complex

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Histidine-rich Ca²⁺-binding protein stimulates the transport cycle of SERCA through a conformation-dependent fuzzy complex

Dynamics-driven allostery underlies pre-activation of the regulatory Ca²⁺-ATPase/phospholamban complex