Abstract
Maurocalcine (MCa) isolated from Scorpio maurus palmatus venom shares 82% sequence identity with imperatoxin A. Both scorpion toxins are putative mimics of the II-III loop peptide (termed peptide A (pA)) of α1s-dihydropyridine receptor and are thought to act at a common site on ryanodine receptor type 1 (RyR1) important for skeletal muscle EC coupling. The relationship between the actions of synthetic MCa (sMCa) and pA on RyR1 were examined. sMCa released Ca2+ from SR vesicles (EC50 = 17.5 nM) in a manner inhibited by micromolar ryanodine or ruthenium red. pA (0.5-40 μM) failed to induce SR Ca2+ release. Rather, pA enhanced Ca2+ loading into SR and fully inhibited Ca2+-, caffeine-, and sMCa-induced Ca2+ release. The two peptides modified single channel gating behavior in distinct ways. With Cs+-carrying current, 10 nM to 1 μM sMCa induced long lived subconductances having 48% of the characteristic full open state and occasional transitions to 29% at either positive or negative holding potentials. In contrast, pA stabilized long lived channel closures with occasional burst transitions to 65% (sl) and 86% (s2) of the full conductance. The actions of pA and sMCa were observed in tandem. sMCa stabilized additional subconductance states proportional to pA-induced subconductances (i.e. 43% of pA-modified s1 and s2 substates), revealing a proportional gating mechanism. [3H]Ryanodine binding and surface plasmon resonance analyses indicated that the peptides did not interact by simple competition for a single class of mutually exclusive sites on RyR1 to produce proportional gating. The actions of sMCa were also observed with ryanodine-modified channels and channels deficient in immunophilin 12-kDa FK506-binding protein. These results provide evidence that sMCa and pA stabilize distinct RyR1 channel states through distinct mechanisms that allosterically stabilize gating states having proportional conductance.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 16095-16106 |
| Number of pages | 12 |
| Journal | Journal of Biological Chemistry |
| Volume | 278 |
| Issue number | 18 |
| DOIs | |
| State | Published - May 2 2003 |
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ASJC Scopus subject areas
- Biochemistry
Cite this
Maurocalcine and peptide A stabilize distinct subconductance states of ryanodine receptor type 1, revealing a proportional gating mechanism. / Chen, Lili; Estève, Eric; Sabatier, Jean Marc; Ronjat, Michel; De Waard, Michel; Allen, Paul D.; Pessah, Isaac N.
In: Journal of Biological Chemistry, Vol. 278, No. 18, 02.05.2003, p. 16095-16106.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Maurocalcine and peptide A stabilize distinct subconductance states of ryanodine receptor type 1, revealing a proportional gating mechanism
AU - Chen, Lili
AU - Estève, Eric
AU - Sabatier, Jean Marc
AU - Ronjat, Michel
AU - De Waard, Michel
AU - Allen, Paul D.
AU - Pessah, Isaac N
PY - 2003/5/2
Y1 - 2003/5/2
N2 - Maurocalcine (MCa) isolated from Scorpio maurus palmatus venom shares 82% sequence identity with imperatoxin A. Both scorpion toxins are putative mimics of the II-III loop peptide (termed peptide A (pA)) of α1s-dihydropyridine receptor and are thought to act at a common site on ryanodine receptor type 1 (RyR1) important for skeletal muscle EC coupling. The relationship between the actions of synthetic MCa (sMCa) and pA on RyR1 were examined. sMCa released Ca2+ from SR vesicles (EC50 = 17.5 nM) in a manner inhibited by micromolar ryanodine or ruthenium red. pA (0.5-40 μM) failed to induce SR Ca2+ release. Rather, pA enhanced Ca2+ loading into SR and fully inhibited Ca2+-, caffeine-, and sMCa-induced Ca2+ release. The two peptides modified single channel gating behavior in distinct ways. With Cs+-carrying current, 10 nM to 1 μM sMCa induced long lived subconductances having 48% of the characteristic full open state and occasional transitions to 29% at either positive or negative holding potentials. In contrast, pA stabilized long lived channel closures with occasional burst transitions to 65% (sl) and 86% (s2) of the full conductance. The actions of pA and sMCa were observed in tandem. sMCa stabilized additional subconductance states proportional to pA-induced subconductances (i.e. 43% of pA-modified s1 and s2 substates), revealing a proportional gating mechanism. [3H]Ryanodine binding and surface plasmon resonance analyses indicated that the peptides did not interact by simple competition for a single class of mutually exclusive sites on RyR1 to produce proportional gating. The actions of sMCa were also observed with ryanodine-modified channels and channels deficient in immunophilin 12-kDa FK506-binding protein. These results provide evidence that sMCa and pA stabilize distinct RyR1 channel states through distinct mechanisms that allosterically stabilize gating states having proportional conductance.
AB - Maurocalcine (MCa) isolated from Scorpio maurus palmatus venom shares 82% sequence identity with imperatoxin A. Both scorpion toxins are putative mimics of the II-III loop peptide (termed peptide A (pA)) of α1s-dihydropyridine receptor and are thought to act at a common site on ryanodine receptor type 1 (RyR1) important for skeletal muscle EC coupling. The relationship between the actions of synthetic MCa (sMCa) and pA on RyR1 were examined. sMCa released Ca2+ from SR vesicles (EC50 = 17.5 nM) in a manner inhibited by micromolar ryanodine or ruthenium red. pA (0.5-40 μM) failed to induce SR Ca2+ release. Rather, pA enhanced Ca2+ loading into SR and fully inhibited Ca2+-, caffeine-, and sMCa-induced Ca2+ release. The two peptides modified single channel gating behavior in distinct ways. With Cs+-carrying current, 10 nM to 1 μM sMCa induced long lived subconductances having 48% of the characteristic full open state and occasional transitions to 29% at either positive or negative holding potentials. In contrast, pA stabilized long lived channel closures with occasional burst transitions to 65% (sl) and 86% (s2) of the full conductance. The actions of pA and sMCa were observed in tandem. sMCa stabilized additional subconductance states proportional to pA-induced subconductances (i.e. 43% of pA-modified s1 and s2 substates), revealing a proportional gating mechanism. [3H]Ryanodine binding and surface plasmon resonance analyses indicated that the peptides did not interact by simple competition for a single class of mutually exclusive sites on RyR1 to produce proportional gating. The actions of sMCa were also observed with ryanodine-modified channels and channels deficient in immunophilin 12-kDa FK506-binding protein. These results provide evidence that sMCa and pA stabilize distinct RyR1 channel states through distinct mechanisms that allosterically stabilize gating states having proportional conductance.
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U2 - 10.1074/jbc.M209501200
DO - 10.1074/jbc.M209501200
M3 - Article
VL - 278
SP - 16095
EP - 16106
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 18
ER -