Project description:Here we present the draft genome sequence of Chrysiogenes arsenatis strain DSM 11915, only the second genome sequence from the phylum Chrysiogenetes. This strictly anaerobic organism was isolated from arsenic-contaminated gold mine wastewater and respires arsenate or nitrate instead of oxygen. The assembly contains 2,824,977 bp in 22 scaffolds.
Project description:Ruminiclostridium thermocellum DSM 1313 strain adhE*(EA) expression was studied along with ∆hydG and ∆hydG∆ech mutants strains deposited under GSE54082. All strains have been described in a study entitled Elimination of hydrogenase post-translational modification blocks H2 production and increases ethanol yield in Clostridium thermocellum. Biswas, et .al. Biotechnology for Biofuels 2015 8:20 Ruminiclostridium (Clostridium) thermocellum is a leading candidate organism for implementing a consolidated bioprocessing (CBP) strategy for biofuel production due to its native ability to rapidly consume cellulose and its existing ethanol production pathway. C. thermocellum converts cellulose and cellobiose to lactate, formate, acetate, H2, ethanol, amino acids, and other products. Elimination of the pathways leading to products such as H2 could redirect carbon flux towards ethanol production. Rather than delete each hydrogenase individually, we targeted a hydrogenase maturase gene (hydG), which is involved in converting the three [FeFe] hydrogenase apoenzymes into holoenzymes by assembling the active site. This functionally inactivated all three Fe-Fe hydrogenases simultaneously, as they were unable to make active enzymes. In the ∆hydG mutant, the [NiFe] hydrogenase-encoding ech was also deleted to obtain a mutant that functionally lacks all hydrogenase. The ethanol yield increased nearly 2-fold in ∆hydG∆ech compared to wild type, and H2 production was below the detection limit. Interestingly, ∆hydG and ∆hydG∆ech exhibited improved growth in the presence of acetate in the medium. Transcriptomic and proteomic analysis reveal that genes related to sulfate transport and metabolism were up-regulated in the presence of added acetate in ∆hydG, resulting in altered sulfur metabolism. Further genomic analysis of this strain revealed a mutation in the bi-functional alcohol/aldehyde dehydrogenase adhE gene, resulting in a strain with both NADH- and NADPH-dependent alcohol dehydrogenase activities, whereas the wild type strain can only utilize NADH. This is the exact same adhE mutation found in ethanol-tolerant C. thermocellum strain E50C, but ∆hydG∆ech is not more ethanol tolerant than the wild type. Targeting protein post-translational modification is a promising new approach to target multiple enzymes simultaneously for metabolic engineering. This GEO study pertains to expression profiles generated for C. thermocellum DSM 1313 strain adhE*(EA)
Project description:We advance a three gene model of arsenate tolerance in rice based on testing root growth of 108 recombinant inbred lines (RILs) of the Bala x Azucena population. Marker genotype at 3 loci determined arsenate tolerance in 99% of RILs tested. Interestingly, plants must inherit 2, but any two alleles from the tolerant parent (Bala) to have the tolerant phenotype. Challenging the Affymetrix GeneChip Rice Genome array with Azucena and Bala RNA isolated from control and arsenate treated plants revealed 592 genes 2 fold-upregulated by arsenate and 696 downregulated. The array data was also used to identify which genes are expressed within the three target loci. We used microarrays to detail the gene expression at three locations in the rice genome termed AsTol6.1, AsTol6.2 and AsTol10 in response to 1ppm arsenate. The data was also used to study the global gene expression of the two varieties of rice, Azucena and Bala, in the presence of 1ppm arsenate. Keywords: Hydroponics, 0 and 1ppm sodium arsenate, Rice varieties Azucena and Bala
Project description:Stress constantly challenges plant adaptation to the environment. Of all stress types, arsenic was a major threat during the early evolution of plants. The most prevalent chemical form of arsenic is arsenate, whose similarity to phosphate renders it easily incorporated into cells via the phosphate transporters. Here we found that arsenate stress provokes a notable transposon burst in plants, in coordination with arsenate/phosphate transporter repression, which immediately restricts arsenate uptake. This repression was accompanied by delocalization of the phosphate transporter from the plasma membrane. When arsenate was removed, the system rapidly restored transcriptional expression and membrane localization of the transporter. We identify WRKY6 as an arsenate-responsive transcription factor that mediates arsenate/phosphate transporter gene expression and restricts arsenate-induced transposon activation. Plants therefore have a dual WRKY-dependent signaling mechanism that modulates arsenate uptake and transposon expression, providing a coordinated strategy for arsenate tolerance and transposon gene silencing.
Project description:Arsenic is known as a human carcinogen that easily be exposed by the living organisms through environment and food consumption. The arsenic is transport into the cells via phosphate transporters due to its structural similarity with phosphate in both prokaryotes and eukaryotes. We here evaluated and analyzed the toxicogenomic impacts of arsenate and the role of different phosphate concentrations on arsenic toxicity. Our results showed that arsenic uncoupled phosphate levels which eventually affected the growth rate of yeast cells. Analysis of arsenate levels in the medium over 4 to 10 h of its exposure clearly showed that arsenate was easily taken up by the cells in phosphate limited condition.
Project description:ABSTRACT: Inorganic arsenic is a carcinogen and its ingestion in foods such as rice presents a significant risk to human health. Plants chemically reduce arsenate to arsenite. Using genome-wide association (GWA) mapping of loci controlling natural variation in arsenic accumulation in Arabidopsis thaliana allowed us to identify the arsenate reductase required for this reduction, which we named High Arsenic Content1 (HAC1). Complementation verified the identity of HAC1, and expression in Escherichia coli lacking a functional arsenate reductase confirmed the arsenate reductase activity of HAC1. The HAC1 protein accumulates in the epidermis, the outer cell layer of the root, and also in the pericycle cells surrounding the central vascular tissue. Plants lacking HAC1 lose their ability to efflux arsenite from roots, leading to both increased transport of arsenic into the central vascular tissue and on into the shoot. HAC1 therefore functions to reduce arsenate to arsenite in the outer cell layer of the root, facilitating efflux of arsenic as arsenite back into the soil to limit its accumulation in the root and transport to the shoot. Arsenate reduction by HAC1 in the pericycle may play a role in limiting arsenic loading into the xylem. Loss of HAC1 encoded arsenic reduction leads to a significant increase in arsenic accumulation in shoots causing an increased sensitivity to arsenate toxicity. We also confirmed the previous observation that the ACR2 arsenate reductase in A. thaliana plays no detectable role in arsenic metabolism. Further, ACR2 does not interact epistatically with HAC1, since arsenic metabolism in the acr2 hac1 double mutant is disrupted in an identical manner to that described for the hac1 single mutant. Our identification of HAC1 and its associated natural variation provides an important new resource for the development of low arsenic containing food stuffs such as rice.