Intrinsic Disorder of the Neuronal SNARE Protein SNAP25a in its Pre-fusion Conformation.
J Mol Biol
; 435(10): 168069, 2023 05 15.
Article
em En
| MEDLINE
| ID: mdl-37003471
ABSTRACT
The neuronal SNARE protein SNAP25a (isoform 2) forms part of the SNARE complex eliciting synaptic vesicle fusion during neuronal exocytosis. While the post-fusion cis-SNARE complex has been studied extensively, little is known about the pre-fusion conformation of SNAP25a. Here we analyze monomeric SNAP25a by NMR spectroscopy, further supported by small-angle X-ray scattering (SAXS) experiments. SAXS data indicate that monomeric SNAP25 is more compact than a Gaussian chain but still a random coil. NMR shows that for monomeric SNAP25a, before SNAP25a interacts with its SNARE partners to drive membrane fusion, only the N-terminal part (region A5 to V36) of the first SNARE motif, SN1 (L11 - L81), is helical, comprising two α-helices (ranging from A5 to Q20 and S25 toV36). From E37 onwards, SNAP25a is mostly disordered and displays high internal flexibility, including the C-terminal part of SN1, almost the entire second SNARE motif (SN2, N144-A199), and the connecting loop region. Apart from the N-terminal helices, only the C-termini of both SN1 (E73 - K79) and SN2 (region T190 - A199), as well as two short regions in the connecting loop (D99 - K102 and E123 - M127) show a weak α-helical propensity (α-helical population < 25%). We speculate that the N-terminal helices (A5 to Q20 and S25 to V36) which constitute the N-terminus of SN1 act as a nucleation site for initiating SNARE zippering.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas SNARE
/
Fusão de Membrana
/
Neurônios
Limite:
Humans
Idioma:
En
Revista:
J Mol Biol
Ano de publicação:
2023
Tipo de documento:
Article
País de afiliação:
Alemanha