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

SASDJL6 – Sarcomeric F-actin crosslinking protein α-actinin-2 (spectrin repeat rod domain, rod-α-actinin-2)

Rod domain of α-actinin-2
MWI(0) 103 kDa
MWexpected 112 kDa
VPorod 214 nm3
log I(s) 1.70×10-1 1.70×10-2 1.70×10-3 1.70×10-4
Rod domain of α-actinin-2 small angle scattering data  s, nm-1
ln I(s)
Rod domain of α-actinin-2 Guinier plot ln 1.70×10-1 Rg: 6.7 nm 0 (6.7 nm)-2 s2
(sRg)2I(s)/I(0)
Rod domain of α-actinin-2 Kratky plot 1.104 0 √3 sRg
p(r)
Rod domain of α-actinin-2 pair distance distribution function Rg: 7.2 nm 0 Dmax: 27.2 nm

Data validation

Fits and models

log I(s)
 s, nm-1
Rod domain of α-actinin-2 PDB (PROTEIN DATA BANK) model
log I(s)
 s, nm-1
Rod domain of α-actinin-2 DAMFILT model
Synchrotron SAXS data from solutions of the rod domain of α-actinin-2 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). One solute concentration of 1.12 mg/ml was measured at 20°C. 28 successive 0.045 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.

A concentration series (0.3, 0.6, 1.1 and 3.3 mg/ml) were also measured.

Rod domain of α-actinin-2 (rod-α-actinin-2)
Mol. type   Protein
Organism   Homo sapiens
Olig. state   Dimer
Mon. MW   56.1 kDa
 
UniProt   P35609 (274-746)
Sequence   FASTA
 
PDB ID   1HCI