Structural basis for the Golgi membrane recruitment of Sly1p by Sed5p.
Cytosolic Sec1/munc18-like proteins (SM proteins) are recruited to membrane fusion sites by interaction with syntaxin-type SNARE proteins, constituting indispensable positive regulators of intracellular membrane fusion. Here we present the crystal structure of the yeast SM protein Sly1p in complex with a short N-terminal peptide derived from the Golgi-resident syntaxin Sed5p. Sly1p folds, similarly to neuronal Sec1, into a three-domain arch-shaped assembly, and Sed5p interacts in a helical conformation predominantly with domain I of Sly1p on the opposite site of the nSec1/syntaxin-1-binding site. Sequence conservation of the major interactions suggests that homologues of Sly1p as well as the paralogous Vps45p group bind their respective syntaxins in the same way. Furthermore, we present indirect evidence that nSec1 might be able to contact syntaxin 1 in a similar fashion. The observed Sly1p-Sed5p interaction mode therefore indicates how SM proteins can stay associated with the assembling fusion machinery in order to participate in late fusion steps.
Bracher
Andreas
A
European Molecular Biology Laboratory, 6 rue Jules Horowitz, 38042 Grenoble, France. bracher@embl-grenoble.fr
Weissenhorn
Winfried
W
D000595:Amino Acid Sequence; D000954:Antigens, Surface / Q000378:metabolism; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000502:physiology; D018360:Crystallography, X-Ray; D019143:Evolution, Molecular; D046911:Macromolecular Substances; D008561:Membrane Fusion; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D051938:Munc18 Proteins; D009419:Nerve Tissue Proteins / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D050765:Qa-SNARE Proteins; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D050600:SNARE Proteins; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000502:physiology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D050827:Syntaxin 1; D033921:Vesicular Transport Proteins
D000954:Antigens, Surface; D002352:Carrier Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D051938:Munc18 Proteins; D009419:Nerve Tissue Proteins; D050765:Qa-SNARE Proteins; D011993:Recombinant Fusion Proteins; C072520:SLY1 protein, S cerevisiae; D050600:SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; C077554:Sed5 protein, S cerevisiae; D050827:Syntaxin 1; D033921:Vesicular Transport Proteins