Clocked stepping of an artificial protein walker along a DNA track.

Nilsson P, Robertson NO, Gustafsson N, Davies RB, Liew CW, Lyons A, Eichhorn R, Niman CS, Blab GA, Bromley EHC, Whitten AE Duff AP, Unksov IN, Beech JP, Jönsson P, Böcking T, Höcker B, Woolfson DN, Forde NR, Linke H, Curmi PMG, Nat Nanotechnol (2026) Europe PMC

SASDWM8 – Tumbleweed protein composed of synthetic constructs TW1 and TW2 linked covalently via SpyTag/SpyCatcher

Tumbleweed
MWexperimental 156 kDa
MWexpected 133 kDa
VPorod 190 nm3
log I(s) 6.13×10-2 6.13×10-3 6.13×10-4 6.13×10-5
Tumbleweed small angle scattering data  s, nm-1
ln I(s)
Tumbleweed Guinier plot ln 6.14×10-2 Rg: 6.7 nm 0 (6.7 nm)-2 s2
(sRg)2I(s)/I(0)
Tumbleweed Kratky plot 1.104 0 √3 sRg
p(r)
Tumbleweed pair distance distribution function Rg: 6.9 nm 0 Dmax: 27 nm

Data validation

Fits and models

log I(s)
 s, nm-1
Tumbleweed MULTIFOXS model
log I(s)
 s, nm-1
Tumbleweed MULTIFOXS model
Synchrotron SAXS data from solutions of Tumbleweed protein composed of synthetic constructs TW1 and TW2 linked covalently via SpyTag/SpyCatcher in 10 mM HEPES, 150 mM NaCl, 5mM MgCl2, pH 7.4 were collected on the SAXS/WAXS beam line at the Australian Synchrotron storage ring (Melbourne, Australia) using a Pilatus3 S 2M detector at a sample-detector distance of 2.7 m and at a wavelength of λ = 0.10332 nm (I(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle). One solute concentration of 10.00 mg/ml was measured at 20°C. 10 successive 1 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.

TW is a protein formed by covalent linkage of the the proteins TW1 and TW2 via a SpyTag/SpyCatcher. SAXS data was collected at the SAXS/WAXS beamline at the Australian Synchrotron, with Pilatus 2M detector at a SDD of 2680mm, with an incident intensity of ~8 x 10^12 ph/s. A SEC-SAXS setup with sheath flow was used. The running buffer was 10 mM HEPES pH 7.4, 150 mM NaCl, 5mM MgCl2, and 50uL of sample at ~10mg/mL was injected onto a Superdex 200 Increase 5/150 GL running at 0.2mL/min. Buffer scattering frames taken immediately before the void fraction. Sample scattering frames taken at the elution peak over a region of stable Rg using CHROMIX. Data were fit by a 2-state model using MultiFoXS.

Tumbleweed (TW)
Mol. type   Protein
Organism   synthetic construct
Olig. state   Monomer
Mon. MW   132.8 kDa
Sequence   FASTA