Metal ions are essential to life as they augment amino acid protein chemistry and thereby catalyze many difficult biological reactions. As """"""""free"""""""" metal ions are toxic and indiscriminately reactive, critical protein systems have evolved to sequester, chaperone, and regulate metal ion concentrations. Defects in these systems lead to metal ion metabolic disease and result in cellular, tissue, and systemic pathology. The iron-sulfur cluster assembly pathway contains a conserved set of metallochaperone proteins that recognize and insert Fe-S clusters into apo metalloproteins. Our working model is that frataxin (Fxn) binds to a Nfs1/Isd11/Isu2 complex and activates the complex for Fe-S cluster biosynthesis. In this proposal, we aim to build on these results by further developing our in vitro system and providing structural properties for the assembly complexes, mechanistic details for Fe-S cluster synthesis, and determine the basis for the compromised function in Friedreich's ataxia clinical variants. This fundamental research will establish a framework for emerging genetic results and discoveries and provide a basis for understanding defects in iron-sulfur cluster metabolism relevant to human health and disease.

Public Health Relevance

The fundamental research in this proposal will have important public health implications for understanding iron metabolism and mitochondrial dysfunction. Defects in the biogenesis of iron-sulfur clusters are directly associated with cardiovascular and neurodegenerative disease, and contribute to genomic instability, the development of cancer, and aging.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Special Emphasis Panel (ZRG1-BCMB-B (02))
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Anderson, Vernon
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Texas A&M University
Schools of Arts and Sciences
College Station
United States
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Cory, Seth A; Van Vranken, Jonathan G; Brignole, Edward J et al. (2017) Structure of human Fe-S assembly subcomplex reveals unexpected cysteine desulfurase architecture and acyl-ACP-ISD11 interactions. Proc Natl Acad Sci U S A 114:E5325-E5334
Vranish, James N; Russell, William K; Yu, Lusa E et al. (2015) Fluorescent probes for tracking the transfer of iron-sulfur cluster and other metal cofactors in biosynthetic reaction pathways. J Am Chem Soc 137:390-8
Fox, Nicholas G; Chakrabarti, Mrinmoy; McCormick, Sean P et al. (2015) The Human Iron-Sulfur Assembly Complex Catalyzes the Synthesis of [2Fe-2S] Clusters on ISCU2 That Can Be Transferred to Acceptor Molecules. Biochemistry 54:3871-9
Fox, Nicholas G; Das, Deepika; Chakrabarti, Mrinmoy et al. (2015) Frataxin Accelerates [2Fe-2S] Cluster Formation on the Human Fe-S Assembly Complex. Biochemistry 54:3880-9
Bridwell-Rabb, Jennifer; Fox, Nicholas G; Tsai, Chi-Lin et al. (2014) Human frataxin activates Fe-S cluster biosynthesis by facilitating sulfur transfer chemistry. Biochemistry 53:4904-13
Bridwell-Rabb, Jennifer; Iannuzzi, Clara; Pastore, Annalisa et al. (2012) Effector role reversal during evolution: the case of frataxin in Fe-S cluster biosynthesis. Biochemistry 51:2506-14
Tsai, Chi-Lin; Bridwell-Rabb, Jennifer; Barondeau, David P (2011) Friedreich's ataxia variants I154F and W155R diminish frataxin-based activation of the iron-sulfur cluster assembly complex. Biochemistry 50:6478-87
Bridwell-Rabb, Jennifer; Winn, Andrew M; Barondeau, David P (2011) Structure-function analysis of Friedreich's ataxia mutants reveals determinants of frataxin binding and activation of the Fe-S assembly complex. Biochemistry 50:7265-74