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Structure. 2016 Dec 6;24(12):2080-2091. doi: 10.1016/j.str.2016.08.020. Epub 2016 Nov 3.

Structural/Functional Properties of Human NFU1, an Intermediate [4Fe-4S] Carrier in Human Mitochondrial Iron-Sulfur Cluster Biogenesis.

Author information

1
Mitochondrial Proteome Project, Center for Eukaryotic Structural Genomics, University of Wisconsin-Madison, Madison, WI 53706, USA.
2
Department of Molecular Biology and Biochemistry, Center of Advanced Biotechnology and Medicine, Northeast Structural Genomics Consortium, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA.
3
Biochemistry Department, National Magnetic Resonance Facility at Madison, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA.
4
Department of Molecular Biology and Biochemistry, Center of Advanced Biotechnology and Medicine, Northeast Structural Genomics Consortium, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA; Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA. Electronic address: gtm@rutgers.edu.
5
Mitochondrial Proteome Project, Center for Eukaryotic Structural Genomics, University of Wisconsin-Madison, Madison, WI 53706, USA; Biochemistry Department, National Magnetic Resonance Facility at Madison, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA. Electronic address: jmarkley@wisc.edu.

Abstract

Human mitochondrial NFU1 functions in the maturation of iron-sulfur proteins, and NFU1 deficiency is associated with a fatal mitochondrial disease. We determined three-dimensional structures of the N- and C-terminal domains of human NFU1 by nuclear magnetic resonance spectroscopy and used these structures along with small-angle X-ray scattering (SAXS) data to derive structural models for full-length monomeric apo-NFU1, dimeric apo-NFU1 (an artifact of intermolecular disulfide bond formation), and holo-NFUI (the [4Fe-4S] cluster-containing form of the protein). Apo-NFU1 contains two cysteine residues in its C-terminal domain, and two apo-NFU1 subunits coordinate one [4Fe-4S] cluster to form a cluster-linked dimer. Holo-NFU1 consists of a complex of three of these dimers as shown by molecular weight estimates from SAXS and size-exclusion chromatography. The SAXS-derived structural model indicates that one N-terminal region from each of the three dimers forms a tripartite interface. The activity of the holo-NFU1 preparation was verified by demonstrating its ability to activate apo-aconitase.

KEYWORDS:

Fe-S cluster transfer; NMR spectroscopy; iron-sulfur protein biosynthesis; small-angle X-ray scattering

PMID:
27818104
PMCID:
PMC5166578
DOI:
10.1016/j.str.2016.08.020
[Indexed for MEDLINE]
Free PMC Article

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