Interactions between Ca2+-ATPase and the Pentameric Form of Phospholamban in Two-Dimensional Co-Crystals

Stokes, David L.; Pomfret, Andrew J.; Rice, William J.; Glaves, John Paul; Young, Howard S.

doi:10.1529/biophysj.105.079640

Cited by 49 publications

(92 citation statements)

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“…7D). Although several studies show that phospholamban asserts its inhibitory function by binding to SERCA in its monomeric form (2,24,25) there is some evidence that the pentameric form of phospholamban may directly interact with SERCA2a, causing a decrease in the affinity of the pump for Ca 2ϩ (45,52). However, the mechanism of this interaction is not fully understood.…”

Section: Vlcad Deficiency In Mice Leads To Polymorphic and Bidirectiomentioning

confidence: 99%

Polymorphic ventricular tachycardia and abnormal Ca²⁺handling in very-long-chain acyl-CoA dehydrogenase null mice

Werdich¹,

Baudenbacher²,

Dzhura³

et al. 2007

American Journal of Physiology-Heart and Circulatory Physiology

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Patients with mutations in the mitochondrial very-long-chain acyl-CoA dehydrogenase (VLCAD) gene are at risk for cardiomyopathy, myocardial dysfunction, ventricular tachycardia (VT), and sudden cardiac death. The mechanism is not known. Here we report a novel mechanism of VT in mice lacking VLCAD (VLCAD−/−). These mice exhibited polymorphic VT and increased incidence of VT after isoproterenol infusion. Polymorphic VT was induced in 10 out of 12 VLCAD−/− mice (83%) when isoproterenol was used. One out of 10 VLCAD−/− mice with polymorphic VT had VT with the typical bidirectional morphology. At the molecular level, VLCAD−/− cardiomyocytes showed increased levels of cardiac ryanodine receptor 2, phospholamban, and calsequestrin with increased [3H]ryanodine binding in heart microsomes. At the single cardiomyocyte level, VLCAD−/− cardiomyocytes showed significant increase in diastolic indo 1 and fura 2 fluorescence, with increased Ca2+ transient amplitude. These changes were associated with altered Ca2+ dynamics, to include: faster sarcomere contraction, larger time derivative of the upstroke, and shorter time-to-minimum sarcomere length compared with VLCAD+/+ control cells. The L-type Ca2+ current characteristics were not different under voltage-clamp conditions in the two VLCAD genotypes. Sarcoplasmic reticulum Ca2+ load measured as normalized integrated Na+/Ca2+ exchange current after rapid caffeine application was increased by 48% in VLCAD−/− cells. We conclude that intracellular Ca2+ handling represents a possible molecular mechanism of arrhythmias in mice and perhaps in VLCAD-deficient humans.

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Section: Vlcad Deficiency In Mice Leads To Polymorphic and Bidirectiomentioning

confidence: 99%

Polymorphic ventricular tachycardia and abnormal Ca²⁺handling in very-long-chain acyl-CoA dehydrogenase null mice

Werdich¹,

Baudenbacher²,

Dzhura³

et al. 2007

American Journal of Physiology-Heart and Circulatory Physiology

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“…Our studies had focused on the monomeric mutant to study the complex with SERCA, given that the monomer is believed to be responsible for inhibition, as well as to eliminate potential complex equilibria between various oligomers of wt-PLN. However, recent studies suggested that the pentameric form of PLN could play a larger role in SERCA regulation than previously was thought (5). Therefore, we embarked in the elucidation of the structure and topology of the pentamer in lipid bilayers.…”

Section: Discussionmentioning

confidence: 99%

Spectroscopic validation of the pentameric structure of phospholamban

Traaseth¹,

Verardi

Torgersen

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

100

126

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Phospholamban (PLN) regulates calcium translocation within cardiac myocytes by shifting sarco(endo)plasmic reticulum Ca 2؉ -ATPase (SERCA) affinity for calcium. Although the monomeric form of PLN (6 kDa) is the principal inhibitory species, recent evidence suggests that the PLN pentamer (30 kDa) also is able to bind SERCA. To date, several membrane architectures of the pentamer have been proposed, with different topological orientations for the cytoplasmic domain: (i) extended from the bilayer normal by 50 -60°; (ii) continuous ␣-helix tilted 28°relative to the bilayer normal; (iii) pinwheel geometry, with the cytoplasmic helix perpendicular to the bilayer normal and in contact with the surface of the bilayer; and (iv) bellflower structure, in which the cytoplasmic domain helix makes Ϸ20°angle with respect to the membrane bilayer normal. Using a variety of cell membrane mimicking systems (i.e., lipid vesicles, oriented lipid bilayers, and detergent micelles) and a combination of multidimensional solution/solidstate NMR and EPR spectroscopies, we tested the different structural models. We conclude that the pinwheel topology is the predominant conformation of pentameric PLN, with the cytoplasmic domain interacting with the membrane surface. We propose that the interaction with the bilayer precedes SERCA binding and may mediate the interactions with other proteins such as protein kinase A and protein phosphatase 1.Ca 2ϩ -ATPase ͉ EPR ͉ membrane protein ͉ solid-state NMR ͉ protein dynamics C alcium translocation into the sarcoplasmic reticulum of cardiac myocytes is controlled by the sarco(endo)plasmic reticulum Ca 2ϩ -ATPase (SERCA). Phospholamban (PLN) regulates the activity of SERCA by shifting the apparent calcium affinity for the enzyme. This activity is relieved by phosphorylation of PLN at Ser-16 and/or Thr-17 and high calcium concentration within the cytosol. Wild-type PLN (wt-PLN) forms stable homopentamers in lipid bilayers and in detergent micelles, where each monomer is composed of a helical cytoplasmic domain (residues 1-16), a semiflexible loop (residues 17-21), and a helical transmembrane domain (residues 22-52) (1, 2). Mutagenesis, molecular biology, and in vivo studies revealed that the PLN pentamer depolymerizes into active monomers that bind and inhibit SERCA (3). Similar conclusions were reached by in vitro fluorescence studies (4). Recently, Young and coworkers (5) have reported a cocrystal formed by SERCA and PLN pentamer, suggesting that the pentameric species also is able to bind SERCA. Furthermore, Jones and coworkers (6) hypothesized that the PLN pentamer may act as a chloride ion channel, which is supported by the bellflower structure recently determined by Oxenoid and Chou (2).There are four principal proposed structural models of pentameric wt-PLN, which differ primarily in the topology of the more dynamic cytoplasmic domain. In each of these models (shown in Fig. 1), residues 32-52 are in a coiled helix approximately parallel to the bilayer normal. The first model (extended helix/sheet ...

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“…Similarly, the mixture of R14del and wild-type PLN was similar to SERCA in the presence of only R14del (Table 1). For comparison, we evaluated a loss-of-function mutant in the transmembrane domain of PLN, Arg 34 3 Ala (N34A) (46). The persistent effect on SERCA seen for the R9C and R14del mutants was not observed with N34A (supplemental Fig.…”

Section: Table 1 Kinetic Parameters From Hill Plotsmentioning

confidence: 99%

Hydrophobic Imbalance in the Cytoplasmic Domain of Phospholamban Is a Determinant for Lethal Dilated Cardiomyopathy

Ceholski

Trieber

Young

2012

Journal of Biological Chemistry

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Background: Heterozygous mutations in phospholamban cause lethal dilated cardiomyopathy. Results: Hydrophobic substitutions in the cytoplasmic domain of phospholamban lead to loss of inhibition and a dominant negative effect on SERCA. Conclusion: Hydrophobic changes in the cytoplasmic domain of phospholamban appear to be one determinant for hereditary dilated cardiomyopathy. Significance: This may provide a prediction model for genetic testing of patients with heart failure.

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Interactions between Ca2+-ATPase and the Pentameric Form of Phospholamban in Two-Dimensional Co-Crystals

Cited by 49 publications

References 48 publications

Polymorphic ventricular tachycardia and abnormal Ca²⁺handling in very-long-chain acyl-CoA dehydrogenase null mice

Polymorphic ventricular tachycardia and abnormal Ca²⁺handling in very-long-chain acyl-CoA dehydrogenase null mice

Spectroscopic validation of the pentameric structure of phospholamban

Hydrophobic Imbalance in the Cytoplasmic Domain of Phospholamban Is a Determinant for Lethal Dilated Cardiomyopathy

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Interactions between Ca2+-ATPase and the Pentameric Form of Phospholamban in Two-Dimensional Co-Crystals

Cited by 49 publications

References 48 publications

Polymorphic ventricular tachycardia and abnormal Ca2+handling in very-long-chain acyl-CoA dehydrogenase null mice

Polymorphic ventricular tachycardia and abnormal Ca2+handling in very-long-chain acyl-CoA dehydrogenase null mice

Spectroscopic validation of the pentameric structure of phospholamban

Hydrophobic Imbalance in the Cytoplasmic Domain of Phospholamban Is a Determinant for Lethal Dilated Cardiomyopathy

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Product

Resources

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Polymorphic ventricular tachycardia and abnormal Ca²⁺handling in very-long-chain acyl-CoA dehydrogenase null mice

Polymorphic ventricular tachycardia and abnormal Ca²⁺handling in very-long-chain acyl-CoA dehydrogenase null mice