1 research outputs found
Influence of Fluorination on Protein-Engineered Coiled-Coil Fibers
We
describe the design and characterization of fluorinated coiled-coil
proteins able to assemble into robust nano- and microfibers. Fluorination
is achieved biosynthetically by residue-specific incorporation of
5,5,5-trifluoroleucine (TFL). The fluorinated proteins C+TFL and Q+TFL
are highly α-helical as confirmed via circular dichroism (CD)
and more resistant to thermal denaturation compared to their nonfluorinated
counterparts, C and Q. The fluorinated proteins demonstrate enhanced
fiber assembly at pH 8.0 with higher order structure in contrast to
nonfluorinated proteins, which are unable to form fibers under the
same conditions. Ionic strength dependent fiber assembly is observed
for fluorinated as well as wild-type proteins in which the fluorinated
proteins exhibited more stable, thicker fibers. The fluorinated and
nonfluorinated proteins reveal metal ion-dependent small molecule
recognition and supramolecular assemblies. In the presence of Zn (II),
enhanced thermal stability and fiber assembly is observed for the
fluorinated proteins and their nonfluorinated counterparts. Whereas
Ni (II) promotes aggregation with no fiber assembly, the stabilization
of α-helix by Zn (II) results in enhanced binding to curcumin
by the fluorinated proteins. Surprisingly, the nonfluorinated proteins
exhibit multiple-fold increase in curcumin binding in the presence
of Zn (II). In the context of the growing number of protein-based
fiber assemblies, these fluorinated coiled-coil proteins introduce
a new paradigm in the development of highly stable, robust self-assembling
fibers under more physiologically relevant pH conditions that promotes
the binding and release of small molecules in response to external
cues