Homotetrameric Structure of the SNAP-23 N-terminal Coiled-coil Domain

Freedman, Steven J.; Song, Hyun Kyu; Xu, Yangguang; Sun, Zhen Yu J.; Eck, Michael J.

doi:10.1074/jbc.m210483200

Cited by 18 publications

(14 citation statements)

References 34 publications

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“…Asn-589 at the a position and Ser-662 at the d position form hydrogen bonds across the coiled-coil interface to the same residues, with a bond distance of 2.7 and 2.8 Å respectively. Similar inter-coil interaction via hydrogen bond at the d position has also been observed in SNAP25 [35]. On the periphery of the structure, several distinct patterns of polar interactions are evident.…”

Section: Resultssupporting

confidence: 73%

Crystal Structure of a Coiled-Coil Domain from Human ROCK I

Song

et al. 2011

PLoS ONE

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The small GTPase Rho and one of its targets, Rho-associated kinase (ROCK), participate in a variety of actin-based cellular processes including smooth muscle contraction, cell migration, and stress fiber formation. The ROCK protein consists of an N-terminal kinase domain, a central coiled-coil domain containing a Rho binding site, and a C-terminal pleckstrin homology domain. Here we present the crystal structure of a large section of the central coiled-coil domain of human ROCK I (amino acids 535–700). The structure forms a parallel α-helical coiled-coil dimer that is structurally similar to tropomyosin, an actin filament binding protein. There is an unusual discontinuity in the coiled-coil; three charged residues (E613, R617 and D620) are positioned at what is normally the hydrophobic core of coiled-coil packing. We speculate that this conserved irregularity could function as a hinge that allows ROCK to adopt its autoinhibited conformation.

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Section: Resultssupporting

confidence: 73%

Crystal Structure of a Coiled-Coil Domain from Human ROCK I

Song

et al. 2011

PLoS ONE

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“…Second, our deletion mutations, which disrupt the formation of the tetramer, retain substantial function, confirming that the dimeric form of tetherin is sufficient for tethering. Third, although we verified the existence of a stable tetramer in solution in vitro, there is precedent for nonphysiological association of recombinant coiled-coil proteins (27). Nevertheless, we cannot exclude the possibility of a tethering mode in which a tetherin tetramer with eight membrane anchors that partition between virion and host membranes serves as a tether to retain virions close to the host cell membrane (Fig.…”

Section: Discussionmentioning

confidence: 99%

Structural insight into the mechanisms of enveloped virus tethering by tetherin

Yang

Wang

Jia

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

158

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Tetherin/BST2 is a type-II membrane protein that inhibits the release of a range of enveloped viruses, including HIV-1. Here we report three crystal structures of human tetherin, including the fulllength ectodomain, a triple cysteine mutant and an ectodomain truncation. These structures show that tetherin forms a continuous alpha helix encompassing almost the entire ectodomain. Tetherin helices dimerize into parallel coiled coils via interactions throughout the C-terminal portion of the ectodomain. A comparison of the multiple structures of the tetherin dimer reveals inherent constrained flexibility at two hinges positioned at residues A88 and G109. In the crystals, two tetherin ectodomain dimers associate into a tetramer by forming an antiparallel four-helix bundle at their N termini. However, mutagenesis studies suggest that the tetrametric form of tetherin, although potentially contributing to, is not essential for its antiviral activity. Nonetheless, the structural and chemical properties of the N terminus of the ectodomain are important for optimal tethering function. This study provides detailed insight into the mechanisms by which this broad-spectrum antiviral restriction factor can function.transmembrane | disulfide bonds | stability | budding

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“…However, in vitro soluble Q‐SNARE‐motifs (lacking their membrane anchor) do not form an intuitively expected stable Q a Q b Q c or Q x Q y complex, but have the intrinsic property to assemble into several four‐helix bundles [e.g. (Q a ) 2 Q b Q c (7), (Q a ) 2 (Q b ) 2 (8) and (Q a ) 4 (8,9); for a SNAP23 (Q b ) 4 bundle see (10)].…”

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confidence: 99%

Structure and Dynamics of a Two-Helix SNARE Complex in Live Cells

Halemani

Bethani

Rizzoli

et al. 2010

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SNAREs are a superfamily of small membrane proteins catalyzing membrane fusion (1,2). They share as a common feature a conserved stretch of 60-70 amino acids, called the SNARE-motif. Most SNARE-motifs are membrane anchored by a C-terminal transmembrane region (TMR), and a few SNAREs possess two SNAREmotifs linked by a region containing a palmitoylated cysteine cluster for membrane attachment.Each fusion step requires a specific set of three to four SNAREs providing four SNARE-motifs. For instance, neuronal exocytosis is driven by formation of a complex between SNAP25 (containing two SNARE-motifs) and syntaxin 1A at the plasma membrane and vesicle associated synaptobrevin 2.The fusion reaction results in a ternary cis-SNARE complex in which the four SNARE-motifs adopt alpha-helical conformation, forming a parallel, twisted bundle stabilized by 16 layers of interaction (3). All layers are hydrophobic with the exception of a highly conserved central ionic layer to which each of the SNARE-motifs contributes either one out of three glutamines (consecutively named Q a , Q b and Q c ) or an arginine (R). According to their contributed amino acids, the SNAREs have been classified as Q a -(syntaxin), Q b -and Q c -(N-and C-terminal SNARE-motifs of SNAP25, respectively) and R-SNARE (synaptobrevin 2) (4). Retrospectively, the neuronal SNARE complex laid the ground for the structural Q/R-SNARE classification of all SNAREs discovered in the animal kingdom, fungi or plants.Although the post-fusion SNARE complex is well characterized, it is still debated by what sequence of interactions it assembles (5). Because Q-SNAREs form complexes but the R-SNARE-motif does not interact with any of the individual Q-SNAREs [for exception see e.g. (6)], it is generally believed that initially a Q-SNARE complex forms, which then functions as acceptor for the R-SNARE.However, in vitro soluble Q-SNARE-motifs (lacking their membrane anchor) do not form an intuitively expected stable Q a Q b Q c or Q x Q y complex, but have the intrinsic property to assemble into several four-helix bundles [e.g. (Q a ) 2 Q b Q c (7), (Q a ) 2 (Q b ) 2 (8) and (Q a ) 4 (8,9); for a SNAP23 (Q b ) 4 bundle see (10)].More recently, several groups accomplished to prevent the stabilization of Q a Q b Q c complexes into (Q a ) 2 Q b Q c complexes by different approaches. For instance, a Q a Q b Q c complex forms when SNAP25 is immobilized on sepharose beads by anti-SNAP25 antibodies (11), a C-terminal synaptobrevin fragment is used for stabilization (12), SNAP25 is available in large excess over syntaxin (12), or complexes are prepared in supported lipid bilayers containing syntaxin at a very low protein to lipid ratio (13).The latter study even allowed the characterization of single complexes and found several states. In addition to the Q a Q b Q c complex, other complexes were also observed with one of the SNAP25 SNARE-motifs dissociated (in principle representing a Q a Q b or Q a Q c complex). 394 www.traffic.dk

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Homotetrameric Structure of the SNAP-23 N-terminal Coiled-coil Domain

Cited by 18 publications

References 34 publications

Crystal Structure of a Coiled-Coil Domain from Human ROCK I

Crystal Structure of a Coiled-Coil Domain from Human ROCK I

Structural insight into the mechanisms of enveloped virus tethering by tetherin

Structure and Dynamics of a Two-Helix SNARE Complex in Live Cells

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