TY - JOUR
T1 - The N-terminal domains of syntaxin 7 and vti1b form three-helix bundles that differ in their ability to regulate SNARE complex assembly
AU - Antonin, Wolfram
AU - Dulubova, Irina
AU - Araç, Demet
AU - Pabst, Stefan
AU - Plitzner, Juliane
AU - Rizo-Rey, Jose
AU - Jahn, Reinhard
PY - 2002/9/27
Y1 - 2002/9/27
N2 - The SNAREs syntaxin 7, syntaxin 8, vti1b, and endobrevin/VAMP8 function in the fusion of late endosomes. Although the core complex formed by these SNAREs is very similar to the neuronal SNARE complex, it differs from the neuronal complex in that three of the four SNAREs contain extended N-terminal regions of unknown structure and function. Here we show that the N-terminal regions of syntaxin 7, syntaxin 8, and vti1b contain well folded α-helical domains. Multidimensional NMR spectroscopy revealed that in syntaxin 7 and vti1b, the domains form three-helix bundles resembling those of syntaxin 1, Sso1p, and Vam3p. The three-helix bundle domain of vti1b is the first of its kind identified in a SNARE outside the syntaxin family. Only syntaxin 7 adopts a closed conformation, whereas in vti1b and syntaxin 8, the N-terminal domains do not interact with the adjacent SNARE motifs. Accordingly, the rate of SNARE complex assembly is retarded about 7-fold when syntaxin 7 contains its N-terminal domain, whereas the N-terminal domains of vti1b and syntaxin 8 have no influence on assembly kinetics. We conclude that three-helix bundles represent a common fold for SNARE N-terminal domains, not restricted to the syntaxin family. However, they differ in their ability to adopt closed conformations and thus to regulate the assembly of SNARE complexes.
AB - The SNAREs syntaxin 7, syntaxin 8, vti1b, and endobrevin/VAMP8 function in the fusion of late endosomes. Although the core complex formed by these SNAREs is very similar to the neuronal SNARE complex, it differs from the neuronal complex in that three of the four SNAREs contain extended N-terminal regions of unknown structure and function. Here we show that the N-terminal regions of syntaxin 7, syntaxin 8, and vti1b contain well folded α-helical domains. Multidimensional NMR spectroscopy revealed that in syntaxin 7 and vti1b, the domains form three-helix bundles resembling those of syntaxin 1, Sso1p, and Vam3p. The three-helix bundle domain of vti1b is the first of its kind identified in a SNARE outside the syntaxin family. Only syntaxin 7 adopts a closed conformation, whereas in vti1b and syntaxin 8, the N-terminal domains do not interact with the adjacent SNARE motifs. Accordingly, the rate of SNARE complex assembly is retarded about 7-fold when syntaxin 7 contains its N-terminal domain, whereas the N-terminal domains of vti1b and syntaxin 8 have no influence on assembly kinetics. We conclude that three-helix bundles represent a common fold for SNARE N-terminal domains, not restricted to the syntaxin family. However, they differ in their ability to adopt closed conformations and thus to regulate the assembly of SNARE complexes.
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U2 - 10.1074/jbc.M204369200
DO - 10.1074/jbc.M204369200
M3 - Article
C2 - 12114520
AN - SCOPUS:0037184043
SN - 0021-9258
VL - 277
SP - 36449
EP - 36456
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 39
ER -