Molecular basis of isoform-specific μ-conotoxin block of cardiac, skeletal muscle, and brain Na+ channels

μ-Conotoxins (μ-CTXs) block skeletal muscle Na<SUP>+</SUP> channels with an affinity 1-2 orders of magnitude higher than cardiac and brain Na<SUP>+</SUP> channels. Although a number of conserved pore residues are recognized as critical determinants of μ-CTX block, the molecul...

Descripción completa

Guardado en:
Detalles Bibliográficos
Autores principales: Li, Ronald A., Ennis, Irene Lucía, Xue, Tian, Nguyen, Hai M., Tomaselli, Gordon F., Goldin, Alan L., Marbán, Eduardo
Formato: Articulo
Lenguaje:Inglés
Publicado: 2003
Materias:
Ciencias Médicas
m-Conotoxin
DII S5-P linker
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/84561
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-84561
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Médicas
m-Conotoxin
DII S5-P linker
spellingShingle Ciencias Médicas
m-Conotoxin
DII S5-P linker
Li, Ronald A.
Ennis, Irene Lucía
Xue, Tian
Nguyen, Hai M.
Tomaselli, Gordon F.
Goldin, Alan L.
Marbán, Eduardo
Molecular basis of isoform-specific μ-conotoxin block of cardiac, skeletal muscle, and brain Na+ channels
topic_facet Ciencias Médicas
m-Conotoxin
DII S5-P linker
description μ-Conotoxins (μ-CTXs) block skeletal muscle Na<SUP>+</SUP> channels with an affinity 1-2 orders of magnitude higher than cardiac and brain Na<SUP>+</SUP> channels. Although a number of conserved pore residues are recognized as critical determinants of μ-CTX block, the molecular basis of isoform-specific toxin sensitivity remains unresolved. Sequence comparison of the domain II (DII) S5-S6 loops of rat skeletal muscle (μ1, Na<SUB>v</SUB>1.4), human heart (hh1, Na<SUB>v</SUB>1.5), and rat brain (rb1, Na<SUB>v</SUB>1.1) Na<SUP>+</SUP> channels reveals substantial divergence in their N-terminal S5-P linkers even though the P-S6 and C-terminal P segments are almost identical. We used Na<SUB>v</SUB>1.4 as the backbone and systematically converted these DII S5-P isoform variants to the corresponding residues in Na<SUB>v</SUB>1.1 and Na<SUB>v</SUB>1.5. The Na<SUB>v</SUB>1.4→Na<SUB>v</SUB>1.5 variant substitutions V724R, C725S, A728S, D730S, and C731S (Na<SUB>v</SUB>1.4 numbering) reduced block of Na<SUB>v</SUB>1.4 by 4-, 86-, 12-, 185-, and 55-fold respectively, rendering the skeletal muscle isoform more "cardiac-like." Conversely, an Na<SUB>v</SUB>1.5→ Na<SUB>v</SUB>1.4 chimeric construct in which the Na<SUB>v</SUB>1.4 DII S5-P linker replaces the analogous segment in Na<SUB>v</SUB>1.5 showed enhanced μ-CTX block. However, these variant determinants are conserved between Na<SUB>v</SUB>1.1 and Na<SUB>v</SUB>1.4 and thus cannot explain their different sensitivities to μ-CTX. Comparison of their sequences reveals two variants at Na<SUB>v</SUB>1.4 positions 729 and 732: Ser and Asn in Na<SUB>v</SUB>1.4 compared with Thr and Lys in Na<SUB>v</SUB>1.1, respectively. The double mutation S729T/N732K rendered Na<SUB>v</SUB>1.4 more "brain-like" (30-fold ↓ in block), and the converse mutation T925S/K928N in Na<SUB>v</SUB>1.1 reproduced the high affinity blocking phenotype of Na<SUB>v</SUB>1.4. We conclude that the DII S5-P linker, although lying outside the conventional ion-conducting pore, plays a prominent role in μ-CTX binding, thus shaping isoform-specific toxin sensitivity.
format Articulo
Articulo
author Li, Ronald A.
Ennis, Irene Lucía
Xue, Tian
Nguyen, Hai M.
Tomaselli, Gordon F.
Goldin, Alan L.
Marbán, Eduardo
author_facet Li, Ronald A.
Ennis, Irene Lucía
Xue, Tian
Nguyen, Hai M.
Tomaselli, Gordon F.
Goldin, Alan L.
Marbán, Eduardo
author_sort Li, Ronald A.
title Molecular basis of isoform-specific μ-conotoxin block of cardiac, skeletal muscle, and brain Na+ channels
title_short Molecular basis of isoform-specific μ-conotoxin block of cardiac, skeletal muscle, and brain Na+ channels
title_full Molecular basis of isoform-specific μ-conotoxin block of cardiac, skeletal muscle, and brain Na+ channels
title_fullStr Molecular basis of isoform-specific μ-conotoxin block of cardiac, skeletal muscle, and brain Na+ channels
title_full_unstemmed Molecular basis of isoform-specific μ-conotoxin block of cardiac, skeletal muscle, and brain Na+ channels
title_sort molecular basis of isoform-specific μ-conotoxin block of cardiac, skeletal muscle, and brain na+ channels
publishDate 2003
url http://sedici.unlp.edu.ar/handle/10915/84561
work_keys_str_mv AT lironalda molecularbasisofisoformspecificmconotoxinblockofcardiacskeletalmuscleandbrainnachannels
AT ennisirenelucia molecularbasisofisoformspecificmconotoxinblockofcardiacskeletalmuscleandbrainnachannels
AT xuetian molecularbasisofisoformspecificmconotoxinblockofcardiacskeletalmuscleandbrainnachannels
AT nguyenhaim molecularbasisofisoformspecificmconotoxinblockofcardiacskeletalmuscleandbrainnachannels
AT tomaselligordonf molecularbasisofisoformspecificmconotoxinblockofcardiacskeletalmuscleandbrainnachannels
AT goldinalanl molecularbasisofisoformspecificmconotoxinblockofcardiacskeletalmuscleandbrainnachannels
AT marbaneduardo molecularbasisofisoformspecificmconotoxinblockofcardiacskeletalmuscleandbrainnachannels
bdutipo_str Repositorios
_version_ 1764820488907915265

Ejemplares similares