Sec22b-dependent assembly of endoplasmic reticulum Q-SNARE proteins
Sec22b-dependent assembly of endoplasmic reticulum Q-SNARE proteins
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DOI：
10.1042/bj20071304
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发表时间：
2008-02-15
影响因子：
4.1
通讯作者：
Tagaya, Mitsuo
中科院分区：
文献类型：
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作者：
Aoki, Takehiro;Kojima, Masaki;Tagaya, Mitsuo
参与膜融合的可溶性N-乙基马来酰亚胺敏感融合蛋白附着蛋白受体(SNARE)蛋白通常含有一个保守的a-螺旋(SNARE基序)，其两侧是一个C-末端跨膜区。根据其母题的结构特征，它们可分为Q-SNARE和R-SNARE。四个SNARE基序(Qa、b、c和R)的组装被认为是触发膜融合的机制。我们以前已经证明，内质网定位的Synaxin 18(Qa)与BNIP1(QB)、p31w/Use1(QC)、Sec22b(R)和几种外周膜蛋白形成复合体。在本研究中，我们使用下拉分析和圆二色谱研究了Synaxin 18与其他SNARs的相互作用。我们发现，Synaxin 18与Sec22b的结合导致其SNARE基序的α-螺旋性增加，从而导致BNIP I和p31的高亲和力结合位点的形成。这种依赖R-SNARE的Q-SNARE组装与定位于内质网以外细胞器的SNARE组装机制有很大不同。结合Synaxin 18复合体的生理作用，讨论了内质网陷阱组装机制的意义。
SNARE (soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptor) proteins involved in membrane fusion usually contain a conserved a-helix (SNARE motif) that is flanked by a C-terminal transmembrane domain. They can be classified into Q-SNARE and R-SNARE based on the structural property of their motifs. Assembly of four SNARE motifs (Qa, b, c and R) is supposed to trigger membrane fusion. We have previously shown that ER (endoplasmic reticulum)-localized syntaxin 18 (Qa) forms a complex with BNIP1 (Qb), p31w/Use1 (Qc), Sec22b (R) and several peripheral membrane proteins. In the present study, we examined the interaction of syntaxin 18 with other SNAREs using pulldown assays and CD spectroscopy. We found that the association of syntaxin 18 with Sec22b induces an increase in alpha-helicity of their SNARE motifs, which results in the formation of high-affinity binding sites for BNIP I and p31. This R-SNARE-dependent Q-SNARE assembly is quite different from the assembly mechanisms of SNAREs localized in organelles other than the ER. The implication of the mechanism of ER SNARE assembly is discussed in the context of the physiological roles of the syntaxin 18 complex.