scholarly journals Structural basis for assembly of TRAPPII complex and specific activation of GTPase Ypt31/32

2021 ◽  
Author(s):  
Chenchen Mi ◽  
Li Zhang ◽  
Shan Sun ◽  
Guoqiang Huang ◽  
Guangcan Shao ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Bound States ◽  
Structural Basis ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Nucleotide Binding Domain ◽  
Closed Conformation ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Protein Particle

Transport protein particle (TRAPP) complexes belong to the multiprotein tethering complex and have three forms- TRAPPI, TRAPPII and TRAPPIII, which share a core of six TRAPPI proteins. TRAPPII facilitates intra-Golgi and endosome-to-Golgi transports by activating GTPase Ypt31/Ypt32 as the guanine nucleotide exchange factor (GEF) in yeast. Here we present cryo-EM structures of yeast TRAPPII in apo and Ypt32-bound states. All the structures show a dimeric architecture assembled by two triangle shaped monomers, while the monomer in the apo structure exhibits both open and closed conformations, and the monomer in the Ypt32-bound form only captures the closed conformation. Located in the interior of the monomer, Ypt32 binds with both TRAPPI and Trs120 via its nucleotide binding domain and binds with Trs31 of TRAPPI via its hypervariable domain. Combined with functional analysis, the structures provide insights into the assembly of TRAPPII and the mechanism of the specific activation of Ypt31/Ypt32 by TRAPPII.

scholarly journals The guanine nucleotide exchange factor Ric-8A induces domain separation and Ras domain plasticity in Gαi1

2015 ◽  
Vol 112 (5) ◽  
pp. 1404-1409 ◽  
Author(s):  
Ned Van Eps ◽  
Celestine J. Thomas ◽  
Wayne L. Hubbell ◽  
Stephen R. Sprang
Keyword(s):  
G Protein ◽  
Bound States ◽  
Guanine Nucleotide Exchange Factor ◽  
Nucleotide Binding ◽  
Conformational Ensemble ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Exchange Factor ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor

Heterotrimeric G proteins are activated by exchange of GDP for GTP at the G protein alpha subunit (Gα), most notably by G protein-coupled transmembrane receptors. Ric-8A is a soluble cytoplasmic protein essential for embryonic development that acts as both a guanine nucleotide exchange factor (GEF) and a chaperone for Gα subunits of the i, q, and 12/13 classes. Previous studies demonstrated that Ric-8A stabilizes a dynamically disordered state of nucleotide-free Gα as the catalytic intermediate for nucleotide exchange, but no information was obtained on the structures involved or the magnitude of the structural fluctuations. In the present study, site-directed spin labeling (SDSL) together with double electron-electron resonance (DEER) spectroscopy is used to provide global distance constraints that identify discrete members of a conformational ensemble in the Gαi1:Ric-8A complex and the magnitude of structural differences between them. In the complex, the helical and Ras-like nucleotide-binding domains of Gαi1 pivot apart to occupy multiple resolved states with displacements as large as 25 Å. The domain displacement appears to be distinct from that observed in Gαs upon binding of Gs to the β2 adrenergic receptor. Moreover, the Ras-like domain exhibits structural plasticity within and around the nucleotide-binding cavity, and the switch I and switch II regions, which are known to adopt different conformations in the GDP- and GTP-bound states of Gα, undergo structural rearrangements. Collectively, the data show that Ric-8A induces a conformationally heterogeneous state of Gαi and provide insight into the mechanism of action of a nonreceptor Gα GEF.

scholarly journals The guanine-nucleotide-exchange factor BopE from Burkholderia pseudomallei adopts a compact version of the Salmonella SopE/SopE2 fold and undergoes a closed-to-open conformational change upon interaction with Cdc42

2008 ◽  
Vol 411 (3) ◽  
pp. 485-493 ◽  
Author(s):  
Abhishek Upadhyay ◽  
Huan-Lin Wu ◽  
Christopher Williams ◽  
Terry Field ◽  
Edouard E. Galyov ◽  
...  
Keyword(s):  
Conformational Change ◽  
Burkholderia Pseudomallei ◽  
Catalytic Domain ◽  
Guanine Nucleotide Exchange Factor ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Exchange Factor ◽  
Closed Conformation ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor

BopE is a type III secreted protein from Burkholderia pseudomallei, the aetiological agent of melioidosis, a severe emerging infection. BopE is a GEF (guanine-nucleotide-exchange factor) for the Rho GTPases Cdc42 (cell division cycle 42) and Rac1. We have determined the structure of BopE catalytic domain (amino acids 78–261) by NMR spectroscopy and it shows that BopE78–261 comprises two three-helix bundles (α1α4α5 and α2α3α6). This fold is similar to that adopted by the BopE homologues SopE and SopE2, which are GEFs from Salmonella. Whereas the two three-helix bundles of SopE78–240 and SopE269–240 form the arms of a ‘Λ’ shape, BopE78–261 adopts a more closed conformation with substantial interactions between the two three-helix bundles. We propose that arginine and proline residues are important in the conformational differences between BopE and SopE/E2. Analysis of the molecular interface in the SopE78–240–Cdc42 complex crystal structure indicates that, in a BopE–Cdc42 interaction, the closed conformation of BopE78–261 would engender steric clashes with the Cdc42 switch regions. This implies that BopE78–261 must undergo a closed-to-open conformational change in order to catalyse guanine nucleotide exchange. In an NMR titration to investigate the BopE78–261–Cdc42 interaction, the appearance of additional peaks per NH for residues in hinge regions of BopE78–261 indicates that BopE78–261 does undergo a closed-to-open conformational change in the presence of Cdc42. The conformational change hypothesis is further supported by substantial improvement of BopE78–261 catalytic efficiency through mutations that favour an open conformation. Requirement for closed-to-open conformational change explains the 10–40-fold lower kcat of BopE compared with SopE and SopE2.

scholarly journals Structural Basis for the Dual Substrate Specificity of DOCK7 Guanine Nucleotide Exchange Factor

Structure ◽  
2019 ◽  
Vol 27 (5) ◽  
pp. 741-748.e3 ◽  
Author(s):  
Mutsuko Kukimoto-Niino ◽  
Kengo Tsuda ◽  
Kentaro Ihara ◽  
Chiemi Mishima-Tsumagari ◽  
Keiko Honda ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Guanine Nucleotide Exchange Factor ◽  
Structural Basis ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Exchange Factor ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Dual Substrate Specificity ◽  
Dual Substrate

Functional analysis of RalGPS2, a murine guanine nucleotide exchange factor for RalA GTPase

2007 ◽  
Vol 313 (11) ◽  
pp. 2293-2307 ◽  
Author(s):  
Michela Ceriani ◽  
Cristina Scandiuzzi ◽  
Loredana Amigoni ◽  
Renata Tisi ◽  
Giovanna Berruti ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Guanine Nucleotide Exchange Factor ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Exchange Factor ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor
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