| 1. |
- Griese, Julia J., et al.
(författare)
-
X ray reduction correlates with soaking accessibility as judged from four non crystallographically related diiron sites
- 2012
-
Ingår i: METALLOMICS. - : Oxford University Press (OUP). - 1756-5901 .- 1756-591X. ; 4:9, s. 894-898
-
Tidskriftsartikel (refereegranskat)abstract
- X-ray crystallography is extensively used to determine the atomic structure of proteins and their cofactors. Though a commonly overlooked problem, it has been shown that structural damage to a redox active metal site may precede loss of diffractivity by more than an order of magnitude in X-ray dose. Therefore the risk of misassigning redox states is great. Adequate treatment and consideration of this issue is of paramount importance in metalloprotein science, from experimental design to interpretation of the data and results. Some metal sites appear to be much more amenable to reduction than others, but the underlying processes are poorly understood. Here, we have analyzed the four non-crystallographically related diiron sites in a crystal of the ribonucleotide reductase R2F protein from Corynebacterium ammoniagenes. We conclude that the amount of X-ray reduction a metal site suffers correlates with its soaking accessibility. This direct observation supports the hypothesis that a diffusion component is involved in the X-ray reduction process.
|
|
| 2. |
- Hossain, Bakhtiar, et al.
(författare)
-
Environmental arsenic exposure and DNA methylation of the tumor suppressor gene p16 and the DNA repair gene MLH1: effect of arsenic metabolism and genotype.
- 2012
-
Ingår i: Metallomics. - : Oxford University Press (OUP). - 1756-5901 .- 1756-591X. ; 4:11, s. 1167-1175
-
Tidskriftsartikel (refereegranskat)abstract
- Arsenic is carcinogenic, possibly partly through epigenetic mechanisms. We evaluated the effects of arsenic exposure and metabolism on DNA methylation. Arsenic exposure and methylation efficiency in 202 women in the Argentinean Andes were assessed from concentrations of arsenic metabolites in urine (inorganic arsenic, methylarsonic acid [MMA], and dimethylarsinic acid [DMA]), measured by HPLC-ICPMS. Methylation of CpGs of the tumor suppressor gene p16, the DNA repair gene MLH1, and the repetitive elements LINE1 was measured by PCR pyrosequencing of blood DNA. Genotyping (N = 172) for AS3MT was performed using Sequenom™, and gene expression (N = 90) using Illumina DirectHyb HumanHT-12 v3.0. Median arsenic concentration in urine was 230 μg L(-1) (range 10.1-1251). In linear regression analysis, log(2)-transformed urinary arsenic concentrations were positively associated with methylation of p16 (β = 0.14, P = 0.0028) and MLH1 (β = 0.28, P = 0.0011), but not with LINE1. Arsenic concentrations were of borderline significance negatively correlated with expression of p16 (r(s) = -0.20; P = 0.066)), but not with MLH1. The fraction of inorganic arsenic was positively (β = 0.026; P = 0.010) and DMA was negatively (β = -0.017, P = 0.043) associated with p16 methylation with no effect of MMA. Carriers of the slow-metabolizing AS3MT haplotype were associated with more p16 methylation (P = 0.022). Arsenic exposure was correlated with increased methylation, in blood, of genes encoding enzymes that suppress carcinogenesis, and the arsenic metabolism efficiency modified the degree of epigenetic alterations.
|
|
| 3. |
- Högbom, Martin
(författare)
-
Metal use in ribonucleotide reductase R2, di-iron, di-manganese and heterodinuclear-an intricate bioinorganic workaround to use different metals for the same reaction
- 2011
-
Ingår i: METALLOMICS. - : Oxford University Press (OUP). - 1756-5901 .- 1756-591X. ; 3:2, s. 110-120
-
Forskningsöversikt (refereegranskat)abstract
- The ferritin-like superfamily comprises of several protein groups that utilize dinuclear metal sites for various functions, from iron storage to challenging oxidations of substrates. Ribonucleotide reductase R2 proteins use the metal site for the generation of a free radical required for the reduction of ribonucleotides to deoxyriboinucleotides, the building blocks of DNA. This ubiquitous and essential reaction has been studied for over four decades and the R2 proteins were, until recently, generally believed to employ the same cofactor and mechanism for radical generation. In this reaction, a stable tyrosyl radical is produced following activation and cleavage of molecular oxygen at a dinuclear iron site in the protein. Discoveries in the last few years have now firmly established that the radical generating reaction is not conserved among the R2 proteins but that different subgroups, that are structurally very similar, instead employ di-manganese or heterodinuclear Mn-Fe cofactors as radical generators. This is remarkable considering that the protein must exercise a strict control over oxygen activation, reactive metal-oxygen intermediate species and the resulting redox potential of the produced radical equivalent. Given the differences in redox properties between Mn and Fe, use of a different metal for this reaction requires associated adaptations of the R2 protein scaffold and the activation mechanism. Further analysis of the differences in protein sequence between R2 subgroups have also led to the discovery of new groups of R2-like proteins with completely different functions, expanding the chemical repertoire of the ferritin-like superfamily. This review describes the discoveries leading up to the identification of the different Mn-containing R2 protein groups and our current understanding of them. Hypotheses regarding the biochemical rationale to develop these chemically complex alternative solutions are also discussed.
|
|
| 4. |
- Pournara, Angeliki, et al.
(författare)
-
Arsenic-induced suppression of kidney cell proliferation and the transcriptional coregulator MAML1
- 2014
-
Ingår i: Metallomics : integrated biometal science. - : Oxford University Press (OUP). - 1756-591X. ; 6, s. 498-504
-
Tidskriftsartikel (refereegranskat)abstract
- Mastermind-like 1 (MAML1) is a transcriptional coregulator of diverse/multiple activators, such as Notch, p53, myocyte enhancer factor 2C, NF-κB, beta-catenin, papillomavirus E6 proteins, early growth response 1 and runt-related transcription factor 2. Thus, MAML1 functions in various signaling pathways, most of them connected to cell proliferation, which suggests that MAML1 might play a potential role as a cell proliferation marker. In this study we show that MAML1 expression in the kidney correlates in silico with established cell proliferation markers including PCNA, CDC2 and XRCC5 (Ku80). Over-expression of MAML1 increased proliferation of human embryonic kidney (HEK) 293 cells, while MAML1 downregulation by siRNA decreased cell proliferation. Exposure of HEK293 cells to inorganic arsenic (arsenite) showed reduced levels of MAML1, in combination with a decreased proliferation rate. Our findings provide evidence that arsenic can inhibit proliferation of embryonic kidney cells, possibly through reduction of MAML1 gene expression.
|
|
| 5. |
- Rentschler, Gerda, et al.
(författare)
-
Cadmium concentrations in human blood and urine are associated with polymorphisms in zinc transporter genes.
- 2014
-
Ingår i: Metallomics. - : Oxford University Press (OUP). - 1756-5901 .- 1756-591X.
-
Tidskriftsartikel (refereegranskat)abstract
- Background. Variation in susceptibility to cadmium (Cd) toxicity may partly be due to differences in Cd toxicokinetics. Experimental studies indicate that zinc (Zn) homeostasis proteins transport Cd. Objective. To evaluate the potential effect of variation in Zn-transporter genes (SLC39A8 and SLC39A14) on Cd concentrations in blood and urine. Methods. We studied women from the Argentinean Andes [median urinary Cd concentration (U-Cd) = 0.24 μg L(-1); erythrocyte Cd (Ery-Cd) = 0.75 μg L(-1) (n = 172)] and from rural Bangladesh [U-Cd = 0.54 μg L(-1) (n = 359), Ery-Cd = 1.1 μg L(-1) (n = 400)]. Polymorphisms (n = 36) were genotyped with Sequenom. Gene expression was measured in whole blood with Illumina DirectHyb HumanHT-12 v4.0. Results. Polymorphisms in SLC39A8 and SLC39A14 were associated with Ery-Cd concentrations in the Andean population. For SLC39A14, women carrying GT or TT genotypes of rs4872479 had 1.25 [95% confidence interval (CI) = 1.07-1.46] times higher Ery-Cd than women carrying GG. Also, women carrying AG or AA of rs870215 had 1.17 (CI 1.01-1.32) times higher Ery-Cd than those carrying GG. For SLC39A8, women carrying AG or GG of rs10014145 had 1.18 (CI 1.03-1.35) times higher Ery-Cd than those with AA, and carriers of CA or AA of rs233804 showed 1.22 (CI 1.04-1.42) times higher Ery-Cd than CC. The Bangladeshi population had similar, but statistically non-significant associations between some of these SNPs and Ery-Cd. In the Andean population, the genotypes of SLC39A14 rs4872479 and rs870215 associated with lower Ery-Cd showed positive correlations with plasma-Zn (P-Zn) and SLC39A14 expression. Conclusions. Polymorphisms in SLC39A14 and SLC39A8 seemed to affect blood Cd concentrations, for SLC39A14 this effect may occur via differential gene expression.
|
|
| 6. |
- Wojdacz, TK, et al.
(författare)
-
Exposure to arsenic and intra-chromosomal instability in blood
- 2014
-
Ingår i: Metallomics : integrated biometal science. - : Oxford University Press (OUP). - 1756-591X. ; 6:8, s. 1387-1389
-
Tidskriftsartikel (refereegranskat)abstract
- The 450k Chip Analysis Methylation Pipeline (ChAMP) is a novel Illumina Infinium HumanMethylation450 BeadChip data processing algorithm that allows the analysis of copy number alterations (CNAs).
|
|
