Multiple features within the syntaxin Sed5p mediate its Golgi localization

Gao, Guanbin; Banfield, David K

doi:10.1111/tra.12720

Cited by 14 publications

(7 citation statements)

References 75 publications

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“…Both of these manipulations eliminate binding to the Dsl1 complex in vitro (20) but could in principle affect the localization and/or stability of the SNARE in vivo. Despite this limitation, our results highlight the functional importance of N-terminal domains not only for Qa-SNAREs (8,10,45), but for Qb-and Qc-SNAREs as well.…”

Section: Discussionmentioning

confidence: 62%

Structural basis for the binding of SNAREs to the multisubunit tethering complex Dsl1

Travis

DAmico

et al. 2020

Preprint

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Multisubunit tethering complexes (MTCs) are large (250 to >750 kDa), conserved macromolecular machines that are essential for SNARE-mediated membrane fusion in all eukaryotes. MTCs are thought to function as organizers of membrane trafficking, mediating the initial, long-range interaction between a vesicle and its target membrane and promoting the formation of membrane-bridging SNARE complexes. Previously, we reported the structure of the Dsl1 complex, the simplest known MTC, which is essential for COPI-mediated transport from the Golgi to the endoplasmic reticulum (ER). This structure suggested how the Dsl1 complex might function to tether a vesicle to its target membrane by binding at one end to the COPI coat and at the other end to ER SNAREs. Here, we use x-ray crystallography to investigate these Dsl1-SNARE interactions in greater detail. The Dsl1 complex comprises three subunits that together form a twolegged structure with a central hinge. Our results show that distal regions of each leg bind N-terminal Habc domains of the ER SNAREs Sec20 (a Qb-SNARE) and Use1 (a Qc-SNARE). The observed binding modes appear to anchor the Dsl1 complex to the ER target membrane while simultaneously ensuring that both SNAREs are in open conformations with their SNARE motifs available for assembly. The proximity of the two SNARE motifs, and therefore their ability to enter the same SNARE complex, depends on the relative orientation of the two Dsl1 legs.

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Section: Discussionmentioning

confidence: 62%

Structural basis for the binding of SNAREs to the multisubunit tethering complex Dsl1

Travis

DAmico

et al. 2020

Preprint

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“…This is in contrast to lower organisms, such as Saccharomyces cerevisiae, which only express a single isoform of Stx5 (Sed5p). Although Sed5p was originally believed to resemble mammalian Stx5S 13 , it is now clear that it likely more resembles Stx5L, since an N-terminal COPI-binding tribasic motif has been identified in Sed5p 19 . The emergence of a second Stx5 isoform can be traced back to the pacific purple sea urchin, Strongylocentrotus purpuratus, and is also present in the model organism Danio rerio, but not in Drosophila melanogaster nor Caenorhabditis elegans.…”

mentioning

confidence: 99%

Congenital disorder of glycosylation caused by starting site-specific variant in syntaxin-5

et al. 2021

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The SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) protein syntaxin-5 (Stx5) is essential for Golgi transport. In humans, the STX5 mRNA encodes two protein isoforms, Stx5 Long (Stx5L) from the first starting methionine and Stx5 Short (Stx5S) from an alternative starting methionine at position 55. In this study, we identify a human disorder caused by a single missense substitution in the second starting methionine (p.M55V), resulting in complete loss of the short isoform. Patients suffer from an early fatal multisystem disease, including severe liver disease, skeletal abnormalities and abnormal glycosylation. Primary human dermal fibroblasts isolated from these patients show defective glycosylation, altered Golgi morphology as measured by electron microscopy, mislocalization of glycosyltransferases, and compromised ER-Golgi trafficking. Measurements of cognate binding SNAREs, based on biotin-synchronizable forms of Stx5 (the RUSH system) and Förster resonance energy transfer (FRET), revealed that the short isoform of Stx5 is essential for intra-Golgi transport. Alternative starting codons of Stx5 are thus linked to human disease, demonstrating that the site of translation initiation is an important new layer of regulating protein trafficking.

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“…4 h-i, Extended Data Fig. 1, Sed5 ), and Sed5 appears to be independent of COPI for its Golgi localization 24 . A subset of Golgi SNAREs is dependent on the ability of COPI to bind ubiquitin ( Extended Data Fig.…”

Section: Discussionmentioning

confidence: 88%

“…Because of the tail-anchored topology of SNAREs, none of these proteins contain a C-terminal dilysine motif on the cytosolic side of the membrane where it is accessible to COPI. Few sorting signals have been identified in SNARE proteins and how they are incorporated into COPI vesicles is incompletely understood [22][23][24][25][26][27][28][29] . The ArfGAP protein Glo3 may contribute because it is known to interact with COPI, Arf-GTP and SNAREs and is proposed to be part of the priming complex 19 .…”

Section: Introductionmentioning

confidence: 99%

Ubiquitination drives COPI priming and Golgi SNARE localization

Date

Hepowit

et al. 2021

Preprint

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Deciphering mechanisms controlling SNARE localization within the Golgi complex is crucial to understanding protein trafficking patterns within the secretory pathway. SNAREs are also thought to prime COPI assembly to ensure incorporation of these essential cargoes into vesicles but the regulation of these events is poorly understood. Here we report a roles for ubiquitin recognition by COPI in SNARE trafficking and in stabilizing interactions between Arf, COPI, and Golgi SNAREs. The ability of COPI to bind ubiquitin through its N-terminal WD repeat domain of β’COP or through an unrelated ubiquitin-binding domain (UBD) is essential for the proper localization of Golgi SNAREs Bet1 and Gos1. We find that COPI, the ArfGAP Glo3 and multiple Golgi SNAREs are ubiquitinated. Notably, the binding of Arf and COPI to Gos1 is markedly enhanced by ubiquitination of these components. Glo3 is thought to prime COPI-SNARE interactions; however, Glo3 is not enriched in the ubiquitin-stabilized SNARE-Arf-COPI complex but is instead enriched with COPI complexes that lack SNAREs. These results support a new model for how posttranslational modifications drive COPI priming events crucial for Golgi SNARE localization.

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Multiple features within the syntaxin Sed5p mediate its Golgi localization

Cited by 14 publications

References 75 publications

Structural basis for the binding of SNAREs to the multisubunit tethering complex Dsl1

Structural basis for the binding of SNAREs to the multisubunit tethering complex Dsl1

Congenital disorder of glycosylation caused by starting site-specific variant in syntaxin-5

Ubiquitination drives COPI priming and Golgi SNARE localization

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