Charged surface area of maurocalcine determines its interaction with the skeletal ryanodine receptor.
The 33 amino acid scorpion toxin maurocalcine (MCa) has been shown to modify the gating of the skeletal-type ryanodine receptor (RyR1). Here we explored the effects of MCa and its mutants ([Ala(8)]MCa, [Ala(19)]MCa, [Ala(20)]MCa, [Ala(22)]MCa, [Ala(23)]MCa, and [Ala(24)]MCa) on RyR1 incorporated into artificial lipid bilayers and on elementary calcium release events (ECRE) in rat and frog skeletal muscle fibers. The peptides induced long-lasting subconductance states (LLSS) on RyR1 that lasted for several seconds. However, their average length and frequency were decreased if the mutation was placed farther away in the 3D structure from the critical (24)Arg residue. The effect was strongly dependent on the direction of the current through the channel. If the direction was similar to that followed by calcium during release, the peptides were 8- to 10-fold less effective. In fibers long-lasting calcium release events were observed after the addition of the peptides. The average length of these events correlated well with the duration of LLSS. These data suggest that the effect of the peptide is governed by the large charged surface formed by residues Lys(20), Lys(22), Arg(23), Arg(24), and Lys(8). Our observations also indicate that the results from bilayer experiments mimic the in situ effects of MCa on RyR1.
Lukács
Balázs
B
Department of Physiology, Research Centre for Molecular Medicine, Medical and Health Science Centre, University of Debrecen, Debrecen, Hungary.
Sztretye
Mónika
M
Almássy
János
J
Sárközi
Sándor
S
Dienes
Beatrix
B
Mabrouk
Kamel
K
Simut
Cecilia
C
Szabó
László
L
Szentesi
Péter
P
De Waard
Michel
M
Ronjat
Michel
M
Jóna
István
I
Csernoch
László
L
D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015640:Ion Channel Gating / Q000187:drug effects; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D009154:Mutation; D010539:Permeability / Q000187:drug effects; D011485:Protein Binding; D011893:Rana esculenta / Q000033:anatomy & histology / Q000378:metabolism; D051381:Rats; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism*; D012604:Scorpion Venoms / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000633:toxicity; D013499:Surface Properties
D015220:Calcium Channels; D019837:Ryanodine Receptor Calcium Release Channel; D012604:Scorpion Venoms; C406406:maurocalcine; D000252:Calcium-Transporting ATPases; D002118:Calcium