Cells contain hundreds of proteins that require iron cofactors for activity. Iron cofactors are synthesized in the cell, but the pathways involved in distributing heme, iron-sulfur clusters, and ferrous/ferric ions to apoproteins remain incompletely defined. In particular, cytosolic monothiol glutaredoxins and BolA-like proteins have been identified as [2Fe-2S]-coordinating complexes in vitro and iron-regulatory proteins in fungi, but it is not clear how these proteins function in mammalian systems or how this complex might affect Fe-S proteins or the cytosolic Fe-S assembly machinery. To explore these questions, we use quantitative immunoprecipitation and live cell proximitydependent biotinylation to monitor interactions between Glrx3, BolA2, and components of the cytosolic iron-sulfur cluster assembly system. We characterize cytosolic Glrx3⅐BolA2 as a Although hundreds of cellular proteins require iron-containing cofactors for activity (1), the machinery responsible for distributing these cofactors remains relatively obscure. Separate systems must exist for both the mitochondrial and the cytosolic/nuclear compartments and systems must selectively distribute ferrous iron ions, iron-sulfur (Fe-S) centers, and heme.Recent studies indicate that the poly(rC)-binding proteins are involved in the distribution of ferrous iron to ferritin, the principal iron storage protein, and to mono-and dinuclear iron enzymes in the cytosol of mammalian cells (2-4). Studies in both bakers' yeast and vertebrates indicate that many proteins are involved in the assembly and distribution of Fe-S clusters in the cytosol (5-7). These proteins are structurally and functionally conserved across many species. One protein class, the monothiol glutaredoxins, has been functionally implicated in the trafficking of both ionic iron and Fe-S clusters (8 -12).Monothiol glutaredoxins are members of the thioredoxin (Trx) 3 -fold family of proteins. Most members of the Trx family utilize a dithiol active site to catalyze the oxido-reduction of thiol-disulfide residues. In contrast, monothiol glutaredoxins contain a Cys-Gly-Phe-Ser active site that lacks catalytic activity and instead coordinates a [2Fe-2S] cluster via the active site cysteine and the sulfhydryl residue of a molecule of glutathione, which is non-covalently bound adjacent to the glutaredoxin active site (10,(13)(14)(15). In vitro analysis of this Fe-S-containing species indicates that two glutathione-bound glutaredoxin proteins can coordinate a single [2Fe-2S] cluster as a bridging complex. In eukaryotes, distinct monothiol glutaredoxins are expressed in the mitochondria and cytosol. Genetic evidence suggests that mitochondrial glutaredoxins are involved in the transfer of newly assembled Fe-S clusters to recipient apoproteins (8,9,16,17). Cytosolic monothiol glutaredoxins differ from their mitochondrial paralogs in that they contain an amino-terminal Trx-like domain followed by one or more glutaredoxin domains. Studies in fungi suggest these proteins are involved in iron homeostasis.Th...

Hundreds of cellular proteins require iron (Fe) cofactors for activity, and cells express systems for their assembly and distribution. Molecular details of the cytosolic iron pool used for iron cofactors are lacking, but iron chaperones of the poly rC-binding protein (PCBP) family play a key role in ferrous ion distribution. Here we show that, in cells and in vitro , PCBP1 coordinates iron via conserved cysteine and glutamate residues and a molecule of non-covalently bound glutathione (GSH). Proteomics analysis of PCBP1-interacting proteins identified BolA2, which functions, in complex with Glrx3, as a cytosolic [2Fe–2S] cluster chaperone. The Fe–GSH-bound form of PCBP1 complexes with cytosolic BolA2 via a bridging Fe ligand. Biochemical analysis of PCBP1 and BolA2, in cells and in vitro , indicates that PCBP1–Fe–GSH–BolA2 serves as an intermediate complex required for the assembly of [2Fe–2S] clusters on BolA2–Glrx3, thereby linking the ferrous iron and Fe–S distribution systems in cells.

Pediculosis is a prevalent parasitic infestation of humans, which is increasing due, in part, to the selection of lice resistant to either the pyrethrins or pyrethroid insecticides by the knockdown resistance (kdr) mechanism. To determine the extent and magnitude of the kdr-type mutations responsible for this resistance, lice were collected from 138 collection sites in 48 U.S. states from 22 July 2013 to 11 May 2015 and analyzed by quantitative sequencing. Previously published data were used for comparisons of the changes in the frequency of the kdr-type mutations over time. Mean percent resistance allele frequency (mean % RAF) values across the three mutation loci were determined from each collection site. The overall mean % RAF (±SD) for all analyzed lice was 98.3 ± 10%. 132/138 sites (95.6%) had a mean % RAF of 100%, five sites (3.7%) had intermediate values, and only a single site had no mutations (0.0%). Forty-two states (88%) had a mean % RAF of 100%. The frequencies of kdr-type mutations did not differ regardless of the human population size that the lice were collected from, indicating a uniformly high level of resistant alleles. The loss of efficacy of the Nix formulation (Prestige Brand, Tarrytown, NY) from 1998 to 2013 was correlated to the increase in kdr-type mutations. These data provide a plausible reason for the decrease in the effectiveness of permethrin in the Nix formulation, which is the parallel increase of kdr-type mutations in lice over time.

Alzheimer’s disease (AD) is a neurodegenerative dementia that affects nearly 50 million people worldwide and is a major source of morbidity, mortality, and healthcare expenditure. While there have been many attempts to develop disease-modifying therapies for late-onset AD, none have so far shown efficacy in humans. However, the long latency between the initial neuronal changes and onset of symptoms, the ability to identify patients at risk based on family history and genetic markers, and the emergence of AD biomarkers for preclinical disease suggests that early risk-reducing interventions may be able to decrease the incidence of, delay or prevent AD. In this review, we discuss six mechanisms—dysregulation of glucose metabolism, inflammation, oxidative stress, trophic factor release, amyloid burden, and calcium toxicity—involved in AD pathogenesis that offer promising targets for risk-reducing interventions. In addition, we offer a blueprint for a multi-modality AD risk reduction program that can be clinically implemented with the current state of knowledge. Focused risk reduction aimed at particular pathological factors may transform AD to a preventable disorder in select cases.