title: Multiple ER-Golgi SNARE transmembrane domains are dispensable for trafficking but required for SNARE recycling.
abstract: The formation of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes between opposing membranes is an essential prerequisite for fusion between vesicles and their target compartments. The composition and length of a SNARE's transmembrane domain (TMD) is also an indicator for their steady-state distribution in cells. The evolutionary conservation of the SNARE TMD, together with the strict requirement of this feature for membrane fusion in biochemical studies, implies that the TMD represents an essential protein module. Paradoxically, we find that for several essential ER- and Golgi-localized SNAREs, a TMD is unnecessary. Moreover, in the absence of a covalent membrane tether, such SNAREs can still support ER-Golgi vesicle transport and recapitulate established genetic interactions. Transport anomalies appear to be restricted to retrograde trafficking, but these defects are overcome by the attachment of a C-terminal lipid anchor to the SNARE. We conclude that the TMD functions principally to support the recycling of Qb-, Qc-, and R-SNAREs and, in so doing, retrograde transport.
authors.affiliation: Division of Life Science, Hong Kong University of Science and Technology, Kowloon, Hong Kong, China.
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.affiliation: Division of Life Science, Hong Kong University of Science and Technology, Kowloon, Hong Kong, China.
authors.forename: Martin S Y
authors.initials: MS
authors.lastname: Lau
authors.affiliation: Division of Life Science, Hong Kong University of Science and Technology, Kowloon, Hong Kong, China bodkb@ust.hk.
authors.forename: David K
authors.initials: DK
authors.lastname: Banfield
mesh_terms: D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000502:physiology; D006056:Golgi Apparatus / Q000378:metabolism / Q000502:physiology; D008561:Membrane Fusion / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism; D011485:Protein Binding; D000072417:Protein Domains; D021381:Protein Transport; D050765:Qa-SNARE Proteins / Q000378:metabolism; D050766:Qb-SNARE Proteins / Q000378:metabolism; D050767:Qc-SNARE Proteins / Q000378:metabolism; D050683:R-SNARE Proteins / Q000378:metabolism; D050600:SNARE Proteins / Q000378:metabolism* / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D050765:Qa-SNARE Proteins; D050766:Qb-SNARE Proteins; D050767:Qc-SNARE Proteins; D050683:R-SNARE Proteins; D050600:SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins