Iron-sulfur clusters are present in more than 300 different types of enzymes or proteins and constitute one of the most ancient, ubiquitous and structurally diverse classes of biological prosthetic groups. However, the most common type of cluster, the cubane-type [Fe4S4] cluster, is particularly sensitive to oxidative degradation. Hence, the process of iron-sulfur biosynthesis and repair is essential to almost all aerobic life forms and is remarkably conserved in prokaryotic and eukaryotic organisms. Three distinct types of iron-sulfur cluster assembly machinery have emerged in bacteria, termed the NIF, ISC and SUF systems, and the ISC and SUF systems form the basis of the eukaryotic mitochondrial and plastid iron-sulfur cluster assembly machineries, respectively. In each case the overall mechanism involves cysteine desulfurase-mediated assembly of transient clusters on scaffold proteins and subsequent transfer of preformed clusters or cluster fragments to apo proteins. However, in no case is the assembly, repair or transfer mechanism understood at the molecular level. The long-term goal of this project is a molecular-level understanding of iron-sulfur cluster biosynthesis and repair using the NIF, ISC and SUF systems, and accessory proteins such as monothiol glutaredoxins and thioredoxin-like Nfu proteins. Elucidating the mechanism of iron-sulfur cluster biosynthesis and repair is central to understanding cellular iron homeostasis and thereby human diseases associated with iron-overload, oxidative stress and defects in the mitochondrial respiratory chain. The approach involves using molecular biology techniques to effect large scale expression and/or site-specific changes in the target enzymes and proteins, biochemical and enzymatic assays, and the application of biophysical spectroscopic techniques (electron paramagnetic resonance, UV-visible absorption, circular dichroism, and magnetically-induced circular dichroism, resonance Raman, M?ssbauer, and mass spectrometry) that can probe the nature, ligation and detailed properties of iron or iron-sulfur centers during cluster biosynthesis, degradation, repair or transfer to acceptor proteins. The objectives are to establish the molecular mechanisms of assembly, degradation, repair, and transfer of iron-sulfur clusters, the specificity of cluster transfer with respect to acceptor proteins, and the means by which iron-sulfur proteins regulate cellular iron homeostasis.

Public Health Relevance

The importance of iron-sulfur clusters to human health stems from their sensitivity to oxidative degradation, their crucial role in iron homeostasis and their involvement in a large number of human enzymes and proteins, particularly those in the mitochondrial respiratory chain. A molecular-level understanding of iron-sulfur cluster biogenesis is essential for understanding a variety of human diseases involving anemia, myopathies and ataxias that arise from defects in iron-sulfur cluster assembly proteins. Moreover, since iron-sulfur clusters are a major target of reactive oxygen species, understanding the degradation and repair process is important for understanding the aging process, age-related neurodegenerative diseases, and other diseases, such as cancer and atherosclerosis, which are associated with oxidative stress.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
2R37GM062524-13
Application #
8760507
Study Section
Macromolecular Structure and Function A Study Section (MSFA)
Program Officer
Anderson, Vernon
Project Start
2001-01-01
Project End
2019-07-31
Budget Start
2014-08-01
Budget End
2015-07-31
Support Year
13
Fiscal Year
2014
Total Cost
$344,606
Indirect Cost
$104,606
Name
University of Georgia
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
004315578
City
Athens
State
GA
Country
United States
Zip Code
30602
Gao, Huanyao; Azam, Tamanna; Randeniya, Sajini et al. (2018) Function and maturation of the Fe-S center in dihydroxyacid dehydratase from Arabidopsis. J Biol Chem 293:4422-4433
Benoit, Stéphane L; Holland, Ashley A; Johnson, Michael K et al. (2018) Iron-sulfur protein maturation in Helicobacter pylori: identifying a Nfu-type cluster carrier protein and its iron-sulfur protein targets. Mol Microbiol 108:379-396
Vaccaro, Brian J; Clarkson, Sonya M; Holden, James F et al. (2017) Biological iron-sulfur storage in a thioferrate-protein nanoparticle. Nat Commun 8:16110
Srivastava, Anurag P; Hardy, Emily P; Allen, James P et al. (2017) Identification of the Ferredoxin-Binding Site of a Ferredoxin-Dependent Cyanobacterial Nitrate Reductase. Biochemistry 56:5582-5592
Wang, Yuzhong; Hickox, Hunter P; Xie, Yaoming et al. (2017) A Stable Anionic Dithiolene Radical. J Am Chem Soc 139:6859-6862
Dlouhy, Adrienne C; Li, Haoran; Albetel, Angela-Nadia et al. (2016) The Escherichia coli BolA Protein IbaG Forms a Histidine-Ligated [2Fe-2S]-Bridged Complex with Grx4. Biochemistry 55:6869-6879
Subramanian, Sowmya; Duin, Evert C; Fawcett, Sarah E J et al. (2015) Spectroscopic and redox studies of valence-delocalized [Fe2S2](+) centers in thioredoxin-like ferredoxins. J Am Chem Soc 137:4567-80
LaVoie, Stephen P; Mapolelo, Daphne T; Cowart, Darin M et al. (2015) Organic and inorganic mercurials have distinct effects on cellular thiols, metal homeostasis, and Fe-binding proteins in Escherichia coli. J Biol Inorg Chem 20:1239-51
Srivastava, Anurag P; Allen, James P; Vaccaro, Brian J et al. (2015) Identification of Amino Acids at the Catalytic Site of a Ferredoxin-Dependent Cyanobacterial Nitrate Reductase. Biochemistry 54:5557-68
Crack, Jason C; Munnoch, John; Dodd, Erin L et al. (2015) NsrR from Streptomyces coelicolor is a nitric oxide-sensing [4Fe-4S] cluster protein with a specialized regulatory function. J Biol Chem 290:12689-704

Showing the most recent 10 out of 22 publications