NfuA, a new factor required for maturing Fe/S proteins in Escherichia coli under oxidative stress and iron starvation conditions.
Iron/sulfur (Fe/S) proteins are central to the functioning of cells in both prokaryotes and eukaryotes. Here, we show that the yhgI gene, which we renamed nfuA, encodes a two-domain protein that is required for Fe/S biogenesis in Escherichia coli. The N-terminal domain resembles the so-called Fe/S A-type scaffold but, curiously, has lost the functionally important Cys residues. The C-terminal domain shares sequence identity with Nfu proteins. Mössbauer and UV-visible spectroscopic analyses revealed that, upon reconstitution, NfuA binds a [4Fe-4S] cluster. Moreover, NfuA can transfer this cluster to apo-aconitase. Mutagenesis studies indicated that the N- and C-terminal domains are important for NfuA function in vivo. Similarly, the functional importance of Cys residues present in the Nfu-like domain was demonstrated in vivo by introducing Cys-->Ser mutations. In vivo investigations revealed that the nfuA gene is important for E. coli to sustain oxidative stress and iron starvation. Also, combining nfuA with either isc or suf mutations led to additive phenotypic deficiencies, indicating that NfuA is a bona fide new player in Isc- and Suf-dependent Fe/S biogenesis pathways. Taken together, these data demonstrate that NfuA intervenes in the maturation of apoproteins in E. coli, allowing them to acquire Fe/S clusters. By taking into account results from numerous previous transcriptomic studies that had suggested a link between NfuA and protein misfolding, we discuss the possibility that NfuA could act as a scaffold/chaperone for damaged Fe/S proteins.
Angelini
Sandra
S
Laboratoire de Chimie Bactérienne, CNRS, UPR 9043, Marseille Cedex, France.
Gerez
Catherine
C
Ollagnier-de Choudens
Sandrine
S
Sanakis
Yiannis
Y
Fontecave
Marc
M
Barras
Frédéric
F
Py
Béatrice
B
D000595:Amino Acid Sequence; D049109:Cell Proliferation; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D007501:Iron / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology*; D008954:Models, Biological; D018832:Molecular Chaperones / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D018384:Oxidative Stress; D017434:Protein Structure, Tertiary; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013696:Temperature
D029968:Escherichia coli Proteins; D007506:Iron-Sulfur Proteins; D018832:Molecular Chaperones; C529800:NfuA protein, E coli; D007501:Iron