Dulubova Irina, Yamaguchi Tomohiro, Gao Yan, Min Sang-Won, Huryeva Iryna, Südhof Thomas C, Rizo Josep
Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA.
EMBO J. 2002 Jul 15;21(14):3620-31. doi: 10.1093/emboj/cdf381.
Soluble N-ethylmaleimide sensitive factor-attachment protein receptors (SNAREs) and Sec1p/Munc18-homologs (SM proteins) play key roles in intracellular membrane fusion. The SNAREs form tight four-helix bundles (core complexes) that bring the membranes together, but it is unclear how this activity is coupled to SM protein function. Studies of the yeast trans-Golgi network (TGN)/endosomal SNARE complex, which includes the syntaxin-like SNARE Tlg2p, have suggested that its assembly requires activation by binding of the SM protein Vps45p to the cytoplasmic region of Tlg2p folded into a closed conformation. Nuclear magnetic resonance and biochemical experiments now show that Tlg2p and Pep12p, a late- endosomal syntaxin that interacts functionally but not directly with Vps45p, have a domain structure characteristic of syntaxins but do not adopt a closed conformation. Tlg2p binds tightly to Vps45p via a short N-terminal peptide motif that is absent in Pep12p. The Tlg2p/Vps45p binding mode is shared by the mammalian syntaxin 16, confirming that it is a Tlg2p homolog, and resembles the mode of interaction between the SM protein Sly1p and the syntaxins Ufe1p and Sed5p. Thus, this mechanism represents the most widespread mode of coupling between syntaxins and SM proteins.
可溶性N - 乙基马来酰亚胺敏感因子附着蛋白受体（SNAREs）和Sec1p/Munc18同源物（SM蛋白）在细胞内膜融合中起关键作用。SNAREs形成紧密的四螺旋束（核心复合物）使膜聚集在一起，但尚不清楚这种活性如何与SM蛋白功能相偶联。对酵母反式高尔基体网络（TGN）/内体SNARE复合物（包括类Syntaxin的SNARE Tlg2p）的研究表明，其组装需要通过SM蛋白Vps45p与折叠成封闭构象的Tlg2p的胞质区域结合来激活。核磁共振和生化实验现在表明，Tlg2p和Pep12p（一种晚期内体Syntaxin，在功能上与Vps45p相互作用但不直接相互作用）具有Syntaxin的结构域特征，但不采用封闭构象。Tlg2p通过Pep12p中不存在的短N端肽基序与Vps45p紧密结合。哺乳动物Syntaxin 16具有与Tlg2p/Vps45p相同的结合模式，证实它是Tlg2p的同源物，并且类似于SM蛋白Sly1p与Syntaxin Ufe1p和Sed5p之间的相互作用模式。因此，这种机制代表了Syntaxin与SM蛋白之间最普遍的偶联模式。
