The scaffold protein IscU is involved in the
assembly/transfer of FeS clusters. IscU exists in both
open and closed conformation. The clusterless open
conformation of IscU adheres to the hydrophobic
surface of polystyrene nanobeads, as observed for other
proteins. Increased accessibility of the ligand cysteines
in bound IscU facilitates assembly of a 2Fe2S cluster,
and the cluster-bearing structured form of IscU does not
interact with the nanobeads, thus ensuring turnover.
The dependence of accelerated cluster assembly on the
nanobeads concentration pointed to steric and crowding
effects as for promoting cluster formation, and confirms
the requirement for structural flexibility of IscU .