Crystal structure of the Habc domain of neuronal syntaxin from the squid Loligo pealei reveals conformational plasticity at its C-terminus

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Crystal structure of the Habc domain of neuronal syntaxin from the squid Loligo pealei reveals conformational plasticity at its C-terminus

Publisher
BioMed Central
Publication Date
Mar 15, 2004
Source
PMC
Keywords
Disciplines
  • Chemistry
  • Medicine
License
Unknown

Abstract

1472-6807-4-6.fm ral ss BioMed CentBMC Structural Biology Open AcceResearch article Crystal structure of the Habc domain of neuronal syntaxin from the squid Loligo pealei reveals conformational plasticity at its C-terminus Andreas Bracher*1,2 and Winfried Weissenhorn1 Address: 1European Molecular Biology Laboratory (EMBL), 6 rue Jules Horowitz, 38042 Grenoble, France and 2Present address: Department of Cellular Biochemistry, Max-Planck-Institute for Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany Email: Andreas Bracher* - [email protected]; Winfried Weissenhorn - [email protected] * Corresponding author Abstract Background: Intracellular membrane fusion processes are mediated by the spatial and temporal control of SNARE complex assembly that results in the formation of a four-helical bundle, composed of one vesicle SNARE and three target membrane SNARE polypeptide chains. Syntaxins are essential t-SNAREs and are characterized by an N-terminal Habc domain, a flexible linker region, a coiled-coil or SNARE motif and a membrane anchor. The N-terminal Habc domain fulfills important regulatory functions while the coiled-coil motif, present in all SNAREs, is sufficient for SNARE complex formation, which is thought to drive membrane fusion. Results: Here we report the crystal structure of the Habc domain of neuronal syntaxin from the squid Loligo pealei, s-syntaxin. Squid Habc crystallizes as a dimer and the monomer structure consists of a three-helical bundle. One molecule is strikingly similar to mammalian syntaxin 1A while the second one shows a structural deviation from the common fold in that the C-terminal part of helix C unwinds and adopts an extended conformation. Conclusion: Conservation of surface residues indicates that the cytosolic part of s-syntaxin can adopt an auto-inhibitory closed conformation that may bind squid neuronal Sec1, s-Sec1, in the same manner as observed in structure of the rat nSec1/syntaxin 1A complex. Furthermore, des

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