Membrane binding and pore forming insertion of PEX5 into horizontal lipid bilayer.
Biol Chem
; 404(2-3): 157-167, 2023 02 23.
Article
em En
| MEDLINE
| ID: mdl-36260915
ABSTRACT
The assembly of the peroxisomal translocon involves the transition of a soluble form of the peroxisomal targeting receptor PEX5 into a membrane-bound form, which becomes an integral membrane component of the import pore for peroxisomal matrix proteins. How this transition occurs is still a mystery. We addressed this question using a artificial horizontal bilayer in combination with fluorescence time-correlated single photon counting (TCSPC) and electrophysiological channel recording. Purified human isoform PEX5L and truncated PEX5L(1-335) lacking the cargo binding domain were selectively labeled with thiol-reactive Atto-dyes. Diffusion coefficients of labeled protein in solution show that PEX5L is monomeric with a rather compact spherical conformation, while the truncated protein appeared in a more extended conformation. Labeled PEX5L and the truncated PEX5L(1-335) bind stably to horizontal bilayer thereby accumulating around 100-fold. The diffusion coefficients of the membrane-bound PEX5L forms are 3-4 times lower than in solution, indicating the formation of larger complexes. Electrophysiological single channel recording shows that membrane-bound labeled and non-labeled PEX5L, but not the truncated PEX5L(1-335), can form ion conducting membrane channels. The data suggest that PEX5L is the pore-forming component of the oligomeric peroxisomal translocon and that spontaneous PEX5L membrane surface binding might be an important step in its assembly.
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Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Peroxissomos
/
Bicamadas Lipídicas
Limite:
Humans
Idioma:
En
Revista:
Biol Chem
Assunto da revista:
BIOQUIMICA
Ano de publicação:
2023
Tipo de documento:
Article
País de afiliação:
Alemanha