Structural Determinants for Activation or Inhibition of Ryanodine Receptors by Basic Residues in the Dihydropyridine Receptor II-III Loop

Green, Daniel; Pace, Suzi M.; Curtis, Suzanne M.; Dulhunty, Angela F.

doi:10.1016/s0006-3495(01)76240-6

Cited by 28 publications

(39 citation statements)

References 22 publications

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“…Fewer NOESY cross-peaks were present in the spectrum for the active fraction 1 of A2(D-R18)-2C 10 ( Figure 2b). These cross-peaks, as well as the a-proton chemical shift, indicate a helical structure between residues 2 and 15 (Casarotto et al, 2001). Thus, the structures of the two residues closest to the lipophilic tail attachment were altered, but the key basic residues required for RyR activation (11-15) remained helical.…”

Section: Structure Of A2(d-r18) Lipid-conjugated Peptidesmentioning

confidence: 98%

“…A sequence of positively charged residues (El-Hayek et al, 1995;Gurrola et al, 1999;Casarotto et al, 2000Casarotto et al, , 2001, and the alignment of the residues along one surface of the molecule (Casarotto et al, 2000;Green et al, 2003), are critical for peptide A to activate RyR channels. Modified A peptides having the most stable a-helical structure are the strongest activators of the RyR and have a surface orientation of positively charged residues similar to that in two scorpion toxins, Imperatoxin A and Maurocalcine (Mosbah et al, 2000;Green et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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Functional implications of modifying RyR‐activating peptides for membrane permeability

Dulhunty

Cengia

Young

et al. 2005

British J Pharmacology

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1 Our aim was to determine whether lipoamino acid conjugation of peptides that are high-affinity activators of ryanodine receptor (RyR) channels would (a) render the peptides membrane permeable, (b) alter their structure or (a) reduce their activity. The peptides correspond to the A region of the II-III loop of the skeletal dihydropyridine receptor. 2 The lipoamino acid conjugation increased the apparent permeability of the peptide across the Caco-2 cell monolayer by up to B20-fold. 3 Nuclear magnetic resonance showed that the a-helical structure of critical basic residues, required for optimal activation of RyRs, was retained after conjugation. 4 The conjugated peptides were more effective in enhancing resting Ca 2 þ release, Ca 2 þ -induced Ca 2 þ release and caffeine-induced Ca 2 þ release from isolated sarcoplasmic reticulum (SR) than their unconjugated counterparts, and significantly enhanced caffeine-induced Ca 2 þ release from mechanically skinned extensor digitorum longus (EDL) fibres. 5 The effect of both conjugated and unconjugated peptides on Ca 2 þ release from skeletal SR was 30-fold greater than their effect on either cardiac Ca 2 þ release or on the Ca 2 þ Mg 2 þ ATPase. 6 A small and very low affinity effect of the peptide in slowing Ca 2 þ uptake by the Ca 2 þ , Mg 2 þ ATPase was exacerbated by lipoamino acid conjugation in both isolated SR and in skinned EDL fibres. 7 The results show that lipoamino acid conjugation of A region peptides increases their membrane permeability without impairing their structure or efficacy in activating skeletal and cardiac RyRs.

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Section: Structure Of A2(d-r18) Lipid-conjugated Peptidesmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Functional implications of modifying RyR‐activating peptides for membrane permeability

Dulhunty

Cengia

Young

et al. 2005

British J Pharmacology

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“…In order to obtain resonance assignments, one-and two-dimensional NMR spectroscopy was performed as described previously [21,25]. 15 N/ 1 H spectra were acquired using a sensitivity-enhanced 15 N-HSQC (heteronuclear single-quantum coherence) pulse sequence [29].…”

Section: Camentioning

confidence: 99%

“…The following peptides were synthesized and purified (by the John Curtin School of Medical Research Biomolecular Resource Facility) as described previously [21,22,25] …”

Section: Introductionmentioning

confidence: 99%

The recombinant dihydropyridine receptor II–III loop and partly structured ‘C’ region peptides modify cardiac ryanodine receptor activity

Dulhunty

Karunasekara

Curtis

et al. 2005

Biochemical Journal

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A physical association between the II-III loop of the DHPR (dihydropryidine receptor) and the RyR (ryanodine receptor) is essential for excitation-contraction coupling in skeletal, but not cardiac, muscle. However, peptides corresponding to a part of the II-III loop interact with the cardiac RyR2 suggesting the possibility of a physical coupling between the proteins. Whether the full II-III loop and its functionally important 'C' region (cardiac DHPR residues 855-891 or skeletal 724-760) interact with cardiac RyR2 is not known and is examined in the present study. Both the cardiac DHPR II-III loop (CDCL) and cardiac peptide (C C ) activated RyR2 channels at concentrations >10 nM. The skeletal DHPR II-III loop (SDCL) activated channels at 100 nM and weakly inhibited at 1 µM. In contrast, skeletal peptide (C S ) inhibited channels at all concentrations when added alone, or was ineffective if added in the presence of C C . Ca 2+ -induced Ca 2+ release from cardiac sarcoplasmic reticulum was enhanced by CDCL, SDCL and the C peptides. The results indicate that the interaction between the II-III loop and RyR2 depends critically on the 'A' region (skeletal DHPR residues 671-690 or cardiac 793-812) and also involves the C region. Structure analysis indicated that (i) both C S and C C are random coil at room temperature, but, at 5• C, have partial helical regions in their N-terminal and central parts, and (ii) secondary-structure profiles for CDCL and SDCL are similar. The data provide novel evidence that the DHPR II-III loop and its C region interact with cardiac RyR2, and that the ability to interact is not isoform-specific.

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“…The C region (residues 720 -765) is strongly implicated in EC coupling (7)(8)(9), and a random coil peptide corresponding to this region modifies the activity of the skeletal RyR (10,11). A second region of the II-III loop, the A region (residues 671-690), is of interest because its corresponding peptide fragment induces Ca 2ϩ release from the SR and enhances current flow through RyR channels with high affinity (5,6,10,(12)(13)(14)(15)(16)(17)(18). Although the A region is not essential for skeletal EC coupling in myocytes (7,9), it may play a role in the DHPR-RyR interaction (8), and it is a useful probe for assessing RyR function (11,17,19).…”

Section: Excitation-contraction (Ec)mentioning

confidence: 99%

Multiple Actions of Imperatoxin A on Ryanodine Receptors

Dulhunty¹,

Curtis²,

Watson³

et al. 2004

Journal of Biological Chemistry

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Imperatoxin A is a high affinity activator of ryanodine receptors. The toxin contains a positively charged surface structure similar to that of the A fragment of skeletal dihydropyridine receptors (peptide A), suggesting that the toxin and peptide could bind to a common site on the ryanodine receptor. However, the question of a common binding site has not been resolved, and the concentration dependence of the actions of the toxin has not been fully explored. We characterize two novel high affinity actions of the toxin on the transient gating of cardiac and skeletal channels, in addition to the well documented lower affinity induction of prolonged substates. Transient activity was (a) enhanced with 0.2-10 nM toxin and (b) depressed by >50 nM toxin. The toxin at >1 nM enhanced Ca 2؉ release from SR in a manner consistent with two independent activation processes. The effects of the toxin on transient activity, as well as the toxin-induced substate, were independent of cytoplasmic Ca 2؉ or Mg 2؉ concentrations or the presence of adenine nucleotide and were seen in diisothiocyanostilbene-2,2-disulfonic acid-modified channels. Peptide A activated skeletal and cardiac channels with 100 nM cytoplasmic Ca 2؉ and competed with Imperatoxin A in the high affinity enhancement of transient channel activity and Ca 2؉ release from SR. In contrast to transient activity, prolonged substate openings induced by the toxin were not altered in the presence of peptide A. The results suggest that Imperatoxin A has three independent actions on ryanodine receptor channels and competes with peptide A for at least one action. Excitation-contraction (EC)1 coupling is the process that facilitates Ca 2ϩ release from the sarcoplasmic reticulum (SR) of muscle fibers following depolarization of the surface/transverse (t-) tubule membrane. A protein-protein interaction between the dihydropyridine receptor (DHPR) and ryanodine receptor (RyR) underlies EC coupling in skeletal muscle. The DHPR L-type Ca 2ϩ channel in the t-tubule membrane detects surface depolarization and transmits a signal to the RyR channel in the SR via an interaction between the cytoplasmic domains of the two proteins. The interacting region of the DHPR is located between the second and third transmembrane repeats in the ␣1

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Structural Determinants for Activation or Inhibition of Ryanodine Receptors by Basic Residues in the Dihydropyridine Receptor II-III Loop

Cited by 28 publications

References 22 publications

Functional implications of modifying RyR‐activating peptides for membrane permeability

Functional implications of modifying RyR‐activating peptides for membrane permeability

The recombinant dihydropyridine receptor II–III loop and partly structured ‘C’ region peptides modify cardiac ryanodine receptor activity

Multiple Actions of Imperatoxin A on Ryanodine Receptors

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