Evidence that late-endosomal SNARE multimerization complex is promoted by transmembrane segments.
Assembly of SNARE proteins into quaternary complexes is a critical step in membrane docking and fusion. Here, we have studied the influence of the transmembrane segments on formation of the late endosomal SNARE complex. The complex was assembled in vitro from full-length recombinant SNAREs and from mutants, where the transmembrane segments were either deleted or replaced by oligo-alanine sequences. We show that endobrevin, syntaxin 7, syntaxin 8, and vti1b readily form a complex. This complex forms a dimer as well as multimeric structures. Interestingly, the natural transmembrane segments accelerate the conversion of the quaternary complex to the dimeric form and are essential for multimerization. These in vitro results suggest that the transmembrane segments are responsible for supramolecular assembly of the endosomal SNARE complex.
Mascia
Laura
L
Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany. lmascia@dfb.unipi.it
Langosch
Dieter
D
D000409:Alanine / Q000378:metabolism; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D019281:Dimerization; D011992:Endosomes / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D050600:SNARE Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D008565:Membrane Proteins; D011994:Recombinant Proteins; D050600:SNARE Proteins; D000409:Alanine