Order from disorder in the sarcomere: FATZ forms a fuzzy but tight complex and phase-separated condensates with α-actinin.

Sponga A, Arolas JL, Schwarz TC, Jeffries CM, Rodriguez Chamorro A, Kostan J, Ghisleni A, Drepper F, Polyansky A, De Almeida Ribeiro E, Pedron M, Zawadzka-Kazimierczuk A, Mlynek G, Peterbauer T, Doto P, Schreiner C, Hollerl E, Mateos B, Geist L, Faulkner G, Kozminski W, Svergun DI, Warscheid B, Zagrovic B, Gautel M, Konrat R, Djinović-Carugo K, Sci Adv 7(22) (2021) Europe PMC

SASDJM6 – Sarcomeric F-actin crosslinking protein α-actinin-2 (half-dimer, hd)

Half dimer of α-actinin-2
MWexperimental 119 kDa
MWexpected 107 kDa
VPorod 172 nm3
log I(s) 1.30×104 1.30×103 1.30×102 1.30×101
Half dimer of α-actinin-2 small angle scattering data  s, nm-1
ln I(s)
Half dimer of α-actinin-2 Guinier plot ln 1.30×104 Rg: 5.3 nm 0 (5.3 nm)-2 s2
(sRg)2I(s)/I(0)
Half dimer of α-actinin-2 Kratky plot 1.104 0 √3 sRg
p(r)
Half dimer of α-actinin-2 pair distance distribution function Rg: 5.7 nm 0 Dmax: 22 nm

Data validation

Fits and models

log I(s)
 s, nm-1
Sarcomeric F-actin crosslinking protein α-actinin-2 (half-dimer, hd) Rg histogram Rg, nm
Half dimer of α-actinin-2 EOM/RANCH model
Half dimer of α-actinin-2 EOM/RANCH model
Half dimer of α-actinin-2 EOM/RANCH model
log I(s)
 s, nm-1
Half dimer of α-actinin-2 CORAL model
log I(s)
 s, nm-1
Half dimer of α-actinin-2 CORAL model
Synchrotron SAXS data from solutions of α-actinin-2 half-dimer in 50 mM Tris-HCl 150 mM NaCl, pH 7.5 were collected on the EMBL P12 beam line at PETRA III (DESY, Hamburg, Germany) using a Pilatus 6M detector at a sample-detector distance of 3 m and at a wavelength of λ = 0.124 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 100.00 μl sample at 5 mg/ml was injected at a 0.50 ml/min flow rate onto a GE Superose 6 Increase 10/300 column at 20°C. 73 successive 0.995 second frames were collected through the main SEC elution peak. The data were normalized to the intensity of the transmitted beam and radially averaged; the scattering of the solvent-blank was subtracted.

Half dimer of α-actinin-2 (hd-α-actinin-2)
Mol. type   Protein
Organism   Homo sapiens
Olig. state   Monomer
Mon. MW   107.0 kDa
 
UniProt   P35609 (1-894)
Sequence   FASTA