X-ray structure of the metastable SEPT14-SEPT7 coiled coil reveals a hendecad region crucial for heterodimerization.

Cavini IA, Winter AJ, D'Muniz Pereira H, Woolfson DN, Crump MP, Garratt RC, Acta Crystallogr D Struct Biol (2023) Europe PMC

SASDR49 – MBP-, SUMO-fused heterodimeric SEPT8-SEPT7 septin coiled coil (MBP-SEPT8c+SUMO-SEPT7c)

Septin-7 (C-terminal domain of SEPT7 fused to SUMO)
Septin-8 (C-terminal domain of SEPT8 fused to MBP)
MWexperimental 74 kDa
MWexpected 81 kDa
VPorod 140 nm3
log I(s) 7.11×10-2 7.11×10-3 7.11×10-4 7.11×10-5
Septin-7 (C-terminal domain of SEPT7 fused to SUMO) Septin-8 (C-terminal domain of SEPT8 fused to MBP) small angle scattering data  s, nm-1
ln I(s)
Septin-7 (C-terminal domain of SEPT7 fused to SUMO) Septin-8 (C-terminal domain of SEPT8 fused to MBP) Guinier plot ln 7.12×10-2 Rg: 5.3 nm 0 (5.3 nm)-2 s2
(sRg)2I(s)/I(0)
Septin-7 (C-terminal domain of SEPT7 fused to SUMO) Septin-8 (C-terminal domain of SEPT8 fused to MBP) Kratky plot 1.104 0 √3 sRg
p(r)
Septin-7 (C-terminal domain of SEPT7 fused to SUMO) Septin-8 (C-terminal domain of SEPT8 fused to MBP) pair distance distribution function Rg: 5.7 nm 0 Dmax: 19.9 nm

Data validation

Fits and models

log I(s)
 s, nm-1
Septin-7 (C-terminal domain of SEPT7 fused to SUMO) Septin-8 (C-terminal domain of SEPT8 fused to MBP) MULTIFOXS model
log I(s)
 s, nm-1
Septin-7 (C-terminal domain of SEPT7 fused to SUMO) Septin-8 (C-terminal domain of SEPT8 fused to MBP) DAMMIN model
Synchrotron SAXS data from solutions of MBP-SEPT8c+SUMO-SEPT7c in 50 mM Tris, 150 mM NaCl, pH 7.5 were collected on the B21 beam line at the Diamond Light Source (Didcot, UK) using a Eiger 4M detector at a sample-detector distance of 3.7 m and at a wavelength of λ = 0.09464 nm (I(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle). In-line size-exclusion chromatography (SEC) SAS was employed. The SEC parameters were as follows: A 45.00 μl sample at 5 mg/ml was injected at a 0.08 ml/min flow rate onto a GE Superdex 200 Increase 3.2/300 column at 15°C. 600 successive 3 second frames were collected. The data were normalized to the intensity of the transmitted beam and radially averaged; the scattering of the solvent-blank was subtracted.

Septin-7 (C-terminal domain of SEPT7 fused to SUMO) (SUMO-SEPT7c)
Mol. type   Protein
Organism   Homo sapiens
Olig. state   Monomer
Mon. MW   25.2 kDa
 
UniProt   Q16181 (335-437)
Sequence   FASTA
 
Septin-8 (C-terminal domain of SEPT8 fused to MBP) (MBP-SEPT8c)
Mol. type   Protein
Organism   Homo sapiens
Olig. state   Monomer
Mon. MW   55.4 kDa
 
UniProt   Q92599 (319-429)
Sequence   FASTA