posted on 2022-08-10, 12:35authored byAnkit Jain, Salma Kassem, Rachel S. Fisher, Biran Wang, Tai-De Li, Tong Wang, Ye He, Shana Elbaum-Garfinkle, Rein V. Ulijn
Supramolecular self-assembly of fibrous components and
liquid–liquid
phase separation are at the extremes of the order-to-disorder spectrum.
They collectively play key roles in cellular organization. It is still
a major challenge to design systems where both highly ordered nanostructures
and liquid–liquid phase-separated domains can coexist. We present
a three-component assembly approach that generates fibrous domains
that exclusively form inside globally disordered, liquid condensates.
This is achieved by creating amphiphilic peptides that combine the
features of fibrillar assembly (the amyloid domain LVFFA) and complex
coacervation (oligo-arginine and adenosine triphosphate (ATP)) in
one peptide, namely, LVFFAR9. When this hybrid peptide
is mixed in different ratios with R9 and ATP, we find that
conditions can be created where fibrous assembly is exclusively observed
inside liquid coacervates. Through fluorescence and atomic force microscopy
characterization, we investigate the dynamic evolution of ordered
and disordered features over time. It was observed that the fibers
nucleate and mature inside the droplets and that these fiber-containing
liquid droplets can also undergo fusion, showing that the droplets
remain liquid-like. Our work thus generates opportunities for the
design of ordered structures within the confined environment of biomolecular
condensates, which may be useful to create supramolecular materials
in defined compartments and as model systems that can enhance understanding
of ordering principles in biology.