Interaction of the conserved oligomeric Golgi complex with t-SNARE Syntaxin5a/Sed5 enhances intra-Golgi SNARE complex stability

Abstract

Tethering factors mediate initial interaction of transport vesicles with target membranes. Soluble N-ethylmaleimide–sensitive fusion protein attachment protein receptors (SNAREs) enable consequent docking and membrane fusion. We demonstrate that the vesicle tether conserved oligomeric Golgi (COG) complex colocalizes and coimmunoprecipitates with intra-Golgi SNARE molecules. In yeast cells, the COG complex preferentially interacts with the SNARE complexes containing yeast Golgi target (t)-SNARE Sed5p. In mammalian cells, hCog4p and hCog6p interact with Syntaxin5a, the mammalian homologue of Sed5p. Moreover, fluorescence resonance energy transfer reveals an in vivo interaction between Syntaxin5a and the COG complex. Knockdown of the mammalian COG complex decreases Golgi SNARE mobility, produces an accumulation of free Syntaxin5, and decreases the steady-state levels of the intra-Golgi SNARE complex. Finally, overexpression of the hCog4p N-terminal Syntaxin5a-binding domain destabilizes intra-Golgi SNARE complexes, disrupting the Golgi. These data suggest that the COG complex orchestrates vesicular trafficking similarly in yeast and mammalian cells by binding to the t-SNARE Syntaxin5a/Sed5p and enhancing the stability of intra-Golgi SNARE complexes.

The COG complex interacts with multiple Golgi SNAREs and enhances fusogenic SNARE complexes assembly

“…As shown in Fig. 1, this analysis reliably confirmed previously established interactions including the interaction of the Cog6 subunit and Stx6 (Laufman et al, 2011), Cog4 and Stx5 (Shestakova et al, 2007), and Cog4 and Sly1 (Laufman et al, 2009). Furthermore, it revealed multiple novel interactions that have not been identified before.…”

“…Among these interactions, only the interaction of COG with Sed5p in yeast and subsequently with Syntaxin 5 (Stx5) in mammals was further characterized and found to be direct and essential (Laufman et al, 2009;Shestakova et al, 2007). To determine whether COG interacts with additional Golgi SNAREs in mammalian cells, we applied a simple approach that relies on co-immunoprecipitation (co-IP) of the COG subunits and the Golgi SNAREs.…”

Cog5–Cog7 crystal structure reveals interactions essential for the function of a multisubunit tethering complex

“…This region might, for example, interact directly with SNARE or SM proteins. It is intriguing in this regard that the region of lobe A where its four subunits interact has been shown to bind the SNARE protein Syntaxin-5 and the SM protein Sly1 (21,44,45). SNARE proteins assemble by forming membrane-bridging α-helical coiled-coil bundles, whereas SM proteins interact with and/or modulate formation of these bundles (46).…”

Engrailed-2 regulates genes related to vesicle formation and transport in cerebellar Purkinje cells

“…Conversely, cog3 was found to be upregulated in L7En-2 mice. As Cog complex proteins are needed for the integrity and dynamics of the Golgi complex (e.g., (Shestakova et al, 2007) and references therein), this is another indication that En-2 overexpression interferes with intracellular transport. Intriguingly, this goes along with a conspicuous absence of Golgi apparatus from the axonal pole of L7En-2 PCs.…”