|
2002
LSU-HHMI Summer Undergraduate Research Program |
| |
 Kevin
Bauerle (Huangen Ding, LSU Dept. of Biological Sciences)
Dimerization of HscA, a Heat Shock Cognate Protein, and
its Potential Role in Iron-Sulfur Cluster Assembly
Iron-sulfur proteins play vital roles in cellular functions
such as DNA repair, transcription regulation, and energy metabolism.
However, exactly how iron-sulfur clusters are assembled in proteins
remains unknown. Here, we carried out a series of experiments
to determine the specific interactions between HscA, IscS, and
IscU. HscA, an hsp70-type molecular chaperone, cysteine desulferase
(IscS), and IscU, a speculated iron-sulfur scaffold protein,
are all part of the iron-sulfur assembly machinery. We investigated
the effects of different concentrations of hydrogen peroxide
and varying incubation periods on the production of the HscA
dimer and the ATPase activity of HscA, both with and without
IscS and L-cysteine. The effect of HscA and IscU on IscS activity
was also characterized. Our results showed that: (1) The dimerization
of HscA occurs in the presence of hydrogen peroxide and greatly
increases the basal ATPase activity of HscA. (2) The addition
of IscS and L-cysteine stimulates the production of the HscA
dimer and increases its basal ATPase activity. However, this
activity is somewhat inhibited by hydrogen peroxide. (3) The
HscA dimer can also be produced in vivo. (4) HscA and IscU stimulate
the cysteine desulferase activity of IscS, and the addition
of both HscA and IscU have a synergistic effect on IscS activity.
Our results provide evidence that there are interactions between
the iron-sulfur assembly proteins IscS, HscA and IscU.
|
|
|
