SNARE Zippering Is Suppressed by a Conformational Constraint that Is Removed by v-SNARE Splitting.
Cell Rep
; 34(2): 108611, 2021 01 12.
Article
em En
| MEDLINE
| ID: mdl-33440145
ABSTRACT
Intracellular vesicle fusion is catalyzed by soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs). Vesicle-anchored v-SNAREs pair with target membrane-associated t-SNAREs to form trans-SNARE complexes, releasing free energy to drive membrane fusion. However, trans-SNARE complexes are unable to assemble efficiently unless activated by Sec1/Munc18 (SM) proteins. Here, we demonstrate that SNAREs become fully active when the v-SNARE is split into two fragments, eliminating the requirement of SM protein activation. Mechanistically, v-SNARE splitting accelerates the zippering of trans-SNARE complexes, mimicking the stimulatory function of SM proteins. Thus, SNAREs possess the full potential to drive efficient membrane fusion but are suppressed by a conformational constraint. This constraint is removed by SM protein activation or v-SNARE splitting. We suggest that ancestral SNAREs originally evolved to be fully active in the absence of SM proteins. Later, a conformational constraint coevolved with SM proteins to achieve the vesicle fusion specificity demanded by complex endomembrane systems.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Transporte Vesicular
/
Proteínas SNARE
Limite:
Humans
Idioma:
En
Revista:
Cell Rep
Ano de publicação:
2021
Tipo de documento:
Article