Adenosine 5'-triphosphate modulation of catalytic intermediates of calcium-adenosine triphosphatase of sarcoplasmic reticulum subsequent to enzyme phosphorylation

McIntosh, David B.; Boyer, Paul D.

doi:10.1021/bi00281a015

Cited by 104 publications

(75 citation statements)

References 31 publications

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“…Considering the low affinity ATP binding to the E-P analog demonstrated in Fig 8, the experiment shown in Fig 9 indicates that low affinity binding of ATP to E1-P-2Ca 2+ accelerates the E1-P to E2-P transition and thereby the consequent phosphoenzyme decay. This is consistent with earlier reports on the effect of ATP secondary binding on phosphoenzyme decay (40)(41)(42).…”

Section: Atp Binding To the Fluoroaluminate Analog Of Epsupporting

confidence: 94%

Concerted Conformational Effects of Ca²⁺and ATP Are Required for Activation of Sequential Reactions in the Ca²⁺ATPase (SERCA) Catalytic Cycle^,

Inesi

Lewis

et al. 2006

Biochemistry

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We relate solution behavior to the crystal structure of the Ca 2+ ATPase (SERCA). We find that nucleotide binding occurs with high affinity through interaction of the adenosine moiety with the N domain, even in the absence of Ca 2+ and Mg 2+ , or to the closed conformation stabilized by thapsigargin (TG). Why then is Ca 2+ crucial for ATP utilization? The influence of AMPPCP, Ca 2+ and Mg 2+ on proteolytic digestion patterns, interpreted in the light of known crystal structures, indicates that a Ca 2+ dependent conformation of the ATPase headpiece is required for a further transition induced by nucleotide binding. This includes opening of the headpiece, which in turn allows inclination of the "A" domain and bending of the "P" domain. Thereby, the phosphate chain of bound ATP acquires an extended configuration allowing the γ-phosphate to reach Asp351 to form a complex including Mg 2+ . We demonstrate by Asp351 mutation that this "productive" conformation of the substrate-enzyme complex is unstable due to electrostatic repulsion at the phosphorylation site. However, this conformation is subsequently stabilized by covalent engagement of the γ-phosphate yielding the phosphoenzyme intermediate. We also demonstrate that the ADP product remains bound with high affinity to the transition state complex, but dissociates with lower affinity as the phosphoenzyme undergoes a further conformational change (i.e., E1P to E2-P transition). Finally, we measured low affinity ATP binding to stable phosphoenzyme analogs, demonstrating that the E1-P to E2-P transition and the enzyme turnover are accelerated by ATP binding to the phosphoenzyme in exchange for ADP.The Ca 2+ ATPase of Sarco-Endoplasmic Reticulum (SERCA) is a membrane bound enzyme that uses ATP as an energy source for Ca 2+ transport. The 100 kD ATPase protein includes ten helical segments partitioned within the membrane bilayer, and a headpiece protruding from the cytosolic membrane surface (1,2). Binding of 2 Ca 2+ is required for enzyme (E) activation, whereby the ATP terminal phosphate is utilized to form a phosphorylated enzyme intermediate (E-P). The bound Ca 2+ then undergoes occlusion and vectorial translocation. The catalytic cycle is completed by hydrolytic cleavage of E-P (3-5)

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Section: Atp Binding To the Fluoroaluminate Analog Of Epsupporting

confidence: 94%

Concerted Conformational Effects of Ca²⁺and ATP Are Required for Activation of Sequential Reactions in the Ca²⁺ATPase (SERCA) Catalytic Cycle^,

Inesi

Lewis

et al. 2006

Biochemistry

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“…This effect explains several reports on secondary activation of phosphoenzyme cleavage by mM ATP (16,17).…”

Section: ؉supporting

confidence: 83%

“…In fact, it was shown by fast kinetic measurements that a chase with mM ATP doubles the rate of hydrolytic cleavage of phosphoenzyme already made by utilization of mol ATP (16). P i º HOH exchange measurements indicate that this effect is due to increased access of the phosphoenzyme to medium water (17). It is likely that this effect of secondary binding is also produced by ADP or pseudosubstrates such as TNP-AMP.…”

Section: Mechanism and Control Of Slippage In The Camentioning

confidence: 98%

The Slippage of the Ca2+ Pump and Its Control by Anions and Curcumin in Skeletal and Cardiac Sarcoplasmic Reticulum

Sumbilla

Lewis

Hammerschmidt

et al. 2002

Journal of Biological Chemistry

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“…The previously published numbers in Table V generally confirm our observations for Ca-ATPase, but they do not support the hypothesis that the observable differences between the calcium and sodium pumps are attributable to a single reaction step. The estimates of P c for calcium pump from different laboratories (Table V, rows 1-3) are in good agreement, and the significantly lower probability of phosphorylating Ca-ATPase than either of the other P-type pumps cannot be explained by the differences in experimental pH (Table V, footnotes), because P c is inversely related to pH for all three pumps (27,39,41). The two more recent studies of the calcium pump are in agreement that P i binds weaker (KЈ P larger) to the calcium pump than to the proton or sodium pump.…”

Section: Figmentioning

confidence: 71%

“…Table V compares the rate constants estimated from the oxygen exchange data for Ca-ATPase in Fig. 3 and the 32 P data characterizing the preparation under "Experimental Procedures" with published values for the calcium (39,40), proton (27), and sodium pumps (13). To facilitate comparing the P-type pumps, KЈ P , K h , and P c are also tabulated.…”

Section: Figmentioning

confidence: 99%

Evidence Calcium Pump Binds Magnesium before Inorganic Phosphate

Nagy

Kane

Tran

et al. 2005

Journal of Biological Chemistry

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Calcium pump-catalyzed18 O exchange between inorganic phosphate and water was studied to test the hypothesis that all P-type pumps bind Mg 2؉ before P i and validate utilization of the rate equation for ordered binding to interpret differences between site-directed mutants and wild-type enzyme. The results were remarkably similar to those obtained earlier with sodium pump (Kasho, V. N., Stengelin, M., Smirnova, I. N., and Faller, L. D. (1997) Biochemistry 36, 8045-8052). The equation for ordered binding of Mg 2؉ before P i fit the data best with only a slight chance (0.6%) of P i binding to apoenzyme. Therefore, P i is the substrate, and Mg 2؉ is an obligatory cofactor. The intrinsic Mg 2؉ dissociation constant from metalloenzyme (K M ‫؍‬ 3.5 ؎ 0.3 mM) was experimentally indistinguishable from the sodium pump value. However, the half-maximal concentration for P i binding to metalloenzyme (K P ‫؍‬ 6.3 ؎ 0.6 mM) was significantly higher (ϳ6-fold), and the probability of calcium pump forming phosphoenzyme from bound P i (P c ‫؍‬ 0.04 ؎ 0.03) was significantly lower (ϳ6-fold) than for the sodium pump. From estimates of the rate constants for phosphorylation and dephosphorylation, the calcium pump appears to catalyze phosphoryl group transfer less efficiently than the sodium pump. Ordered binding of Mg 2؉ before P i implies that both calcium pump and sodium pump form a ternary enzyme⅐metal⅐phos-phate complex, consistent with molecular structures of other haloacid dehalogenase superfamily members that were crystallized with Mg 2؉ and phosphate, or a phosphate analogue, bound.The calcium and sodium pumps are classified as P-type, 1 because the energy required for generating ion gradients across cell membranes is derived from ATP by catalyzing hydrolysis in two, Mg 2ϩ -dependent steps (1). The ␥-phosphoryl group is initially transferred to an aspartyl side chain of the protein in one conformation (E 1 ) forming a covalent phosphoenzyme intermediate. Hydrolysis is completed after a conformational change by transferring the phosphoryl group to water. The second step can be reversed by reacting the second conformation (E 2 ), with P i and can be followed either by radioactive 32 P incorporation into the enzyme, or by stable oxygen isotope ( 18 O) exchange between P i and H 2 O. Phosphorylation by P i is a partial reaction that can be uncoupled from other reactions in the pump cycle experimentally, so that the mechanism is simple enough for derivation of the rate equation. Therefore, measurements combining either 32 P incorporation or 18 O exchange with site-directed mutagenesis are potentially a powerful way of identifying amino acids essential for catalyzing phosphoryl group transfer and of learning their function from estimates of intrinsic constants for interaction of reactants with the enzyme.The problem considered in this report is the mechanism of Mg 2ϩ -dependent phosphorylation by P i . The solution is important because the interpretation of observed differences between mutants and wild-type enzyme depends upon the...

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Adenosine 5'-triphosphate modulation of catalytic intermediates of calcium-adenosine triphosphatase of sarcoplasmic reticulum subsequent to enzyme phosphorylation

Cited by 104 publications

References 31 publications

Concerted Conformational Effects of Ca²⁺and ATP Are Required for Activation of Sequential Reactions in the Ca²⁺ATPase (SERCA) Catalytic Cycle^,

Concerted Conformational Effects of Ca²⁺and ATP Are Required for Activation of Sequential Reactions in the Ca²⁺ATPase (SERCA) Catalytic Cycle^,

The Slippage of the Ca2+ Pump and Its Control by Anions and Curcumin in Skeletal and Cardiac Sarcoplasmic Reticulum

Evidence Calcium Pump Binds Magnesium before Inorganic Phosphate

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Adenosine 5'-triphosphate modulation of catalytic intermediates of calcium-adenosine triphosphatase of sarcoplasmic reticulum subsequent to enzyme phosphorylation

Cited by 104 publications

References 31 publications

Concerted Conformational Effects of Ca2+and ATP Are Required for Activation of Sequential Reactions in the Ca2+ATPase (SERCA) Catalytic Cycle,

Concerted Conformational Effects of Ca2+and ATP Are Required for Activation of Sequential Reactions in the Ca2+ATPase (SERCA) Catalytic Cycle,

The Slippage of the Ca2+ Pump and Its Control by Anions and Curcumin in Skeletal and Cardiac Sarcoplasmic Reticulum

Evidence Calcium Pump Binds Magnesium before Inorganic Phosphate

Contact Info

Product

Resources

About

Concerted Conformational Effects of Ca²⁺and ATP Are Required for Activation of Sequential Reactions in the Ca²⁺ATPase (SERCA) Catalytic Cycle^,

Concerted Conformational Effects of Ca²⁺and ATP Are Required for Activation of Sequential Reactions in the Ca²⁺ATPase (SERCA) Catalytic Cycle^,