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FeoC from Klebsiella pneumoniae contains a [4Fe-4S] cluster.

ABSTRACT: Iron is essential for pathogen survival, virulence, and colonization. Feo is suggested to function as the ferrous iron (Fe(2+)) transporter. The enterobacterial Feo system is composed of 3 proteins: FeoB is the indispensable component and is a large membrane protein likely to function as a permease; FeoA is a small Src homology 3 (SH3) domain protein that interacts with FeoB; FeoC is a winged-helix protein containing 4 conserved Cys residues in a sequence suitable for harboring a putative iron-sulfur (Fe-S) cluster. The presence of an iron-sulfur cluster on FeoC has never been shown experimentally. We report that under anaerobic conditions, the recombinant Klebsiella pneumoniae FeoC (KpFeoC) exhibited hyperfine-shifted nuclear magnetic resonance (NMR) and a UV-visible (UV-Vis) absorbance spectrum characteristic of a paramagnetic center. The electron paramagnetic resonance (EPR) and extended X-ray absorption fine structure (EXAFS) results were consistent only with the [4Fe-4S] clusters. Substituting the cysteinyl sulfur with oxygen resulted in significantly reduced cluster stability, establishing the roles of these cysteines as the ligands for the Fe-S cluster. When exposed to oxygen, the [4Fe-4S] cluster degraded to [3Fe-4S] and eventually disappeared. We propose that KpFeoC may regulate the function of the Feo transporter through the oxygen- or iron-sensitive coordination of the Fe-S cluster.

SUBMITTER: Hsueh KL

PROVIDER: S-EPMC3807426 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature

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FeoC from Klebsiella pneumoniae contains a [4Fe-4S] cluster.

Hsueh Kuang-Lung KL Yu Liang-Kun LK Chen Yung-Han YH Cheng Ya-Hsin YH Hsieh Yin-Cheng YC Ke Shyue-chu SC Hung Kuo-Wei KW Chen Chun-Jung CJ Huang Tai-huang TH

Journal of bacteriology 20130816 20

Iron is essential for pathogen survival, virulence, and colonization. Feo is suggested to function as the ferrous iron (Fe(2+)) transporter. The enterobacterial Feo system is composed of 3 proteins: FeoB is the indispensable component and is a large membrane protein likely to function as a permease; FeoA is a small Src homology 3 (SH3) domain protein that interacts with FeoB; FeoC is a winged-helix protein containing 4 conserved Cys residues in a sequence suitable for harboring a putative iron-s ...[more]

PMID: 23955005

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Project description:The all-ferrous, carbene-capped Fe(4)S(4) cluster, synthesized by Deng and Holm (DH complex), has been studied with density functional theory (DFT). The geometry of the complex was optimized for several electronic configurations. The lowest energy was obtained for the broken-symmetry (BS) configuration derived from the ferromagnetic state by reversing the spin projection of one of the high spin (S(i) = 2) irons. The optimized geometry of the latter configuration contains one unique and three equivalent iron sites, which are both structurally and electronically clearly distinguishable. For example, a distinctive feature of the unique iron site is the diagonal Fe···S distance, which is 0.3 Å longer than for the equivalent irons. The calculated (57)Fe hyperfine parameters show the same 1:3 pattern as observed in the Mössbauer spectra and are in good agreement with experiment. BS analysis of the exchange interactions in the optimized geometry for the 1:3, M(S) = 4, BS configuration confirms the prediction of an earlier study that the unique site is coupled to the three equivalent ones by strong antiferromagnetic exchange (J > 0 in J ?(j<4)?(4)·?(j)) and that the latter are mutually coupled by ferromagnetic exchange (J' < 0 in J' ?(i<j<4)?(i)·?(j)). In combination, these exchange couplings stabilize an S = 4 ground state in which the composite spin of the three equivalent sites (S(123) = 6) is antiparallel to the spin (S(4) = 2) of the unique site. Thus, DFT analysis supports the idea that the unprecedented high value of the spin of the DH complex and, by analogy, of the all-ferrous cluster of the Fe-protein of nitrogenase, results from a remarkably strong dependence of the exchange interactions on cluster core geometry. The structure dependence of the exchange-coupling constants in the Fe(II)-(?(3)-S)(2)-Fe(II) moieties of the all-ferrous clusters is compared with the magneto-structural correlations observed in the data for dinuclear copper complexes. Finally, we discuss two all-ferric clusters in the light of the results for the all-ferrous cluster.

Dataset Information

FeoC from Klebsiella pneumoniae contains a [4Fe-4S] cluster.

Publications

FeoC from Klebsiella pneumoniae contains a [4Fe-4S] cluster.

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