1 research outputs found
Comparison of the Response of Bacterial IscU and SufU to Zn<sup>2+</sup> and Select Transition-Metal Ions
IscU,
the central scaffold protein in the bacterial ISC ironāsulfur
(FeāS) cluster biosynthesis system, has long been recognized
to bind a Zn<sup>2+</sup> ion at its active site. While initially
regarded as an artifact, Zn<sup>2+</sup> binding has been shown to
induce stabilization of the IscU structure that may mimic a state
biologically relevant to IscUās role in FeāS cluster
biosynthesis. More recent studies have revealed that SufU, a homologous
protein involved in FeāS cluster biosynthesis in Gram-positive
bacteria, also binds a Zn<sup>2+</sup> ion with structural implications.
Given the widespread occurrence of the āIscU-likeā protein
fold, particularly among FeāS cluster biosynthesis systems,
an interesting question arises as to whether Zn<sup>2+</sup> ion binding
and the resulting structural alterations are common properties in
IscU-like proteins. Interactions between IscU and specific metal ions
are investigated and compared side-by-side with those of SufU from
a representative Gram-positive bacterium in the phylum <i>Firmicutes</i>. These studies were extended with additional transition metal ions
chosen to investigate the influence of coordination geometry on selectivity
for binding at the active sites of IscU and SufU. Monitoring and comparing
the conformational behavior and stabilization afforded by different
transition metal ions upon IscU and SufU revealed similarities between
the two proteins and suggest that metal-dependent conformational transitions
may be characteristic of U-type proteins involved in FeāS cluster
biosynthesis