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1. Arsenite oxidation regulator AioR regulates bacterial chemotaxis towards arsenite in Agrobacterium tumefaciens GW4

   Article | OPEN | Published: 03 March 2017 Shi, K; Fan, X; Qiao, Z; Han, Y; McDermott, TR; Wang, Q; Wang, G. (March 2017, Scientific reports)

   Some arsenite [As(III)]-oxidizing bacteria exhibit positive chemotaxis towards As(III), however, the related As(III) chemoreceptor and regulatory mechanism remain unknown. The As(III)-oxidizing bacterium Agrobacterium tumefaciens GW4 displays positive chemotaxis towards 0.5–2 mM As(III). Genomic analyses revealed a putative chemoreceptor-encoding gene, mcp, located in the arsenic gene island and having a predicted promoter binding site for the As(III) oxidation regulator AioR. Expression of mcp and other chemotaxis related genes (cheA, cheY2 and fliG) was inducible by As(III), but not in the aioR mutant. Using capillary assays and intrinsic tryptophan fluorescence spectra analysis, Mcp was confirmed to be responsible for chemotaxis towards As(III) and to bind As(III) (but not As(V) nor phosphate) as part of the sensing mechanism. A bacterial one-hybrid system technique and electrophoretic mobility shift assays showed that AioR interacts with the mcp regulatory region in vivo and in vitro, and the precise AioR binding site was confirmed using DNase I foot-printing. Taken together, these results indicate that this Mcp is responsible for the chemotactic response towards As(III) and is regulated by AioR. Additionally, disrupting the mcp gene affected bacterial As(III) oxidation and growth, inferring that Mcp may exert some sort of functional connection between As(III) oxidation and As(III) chemotaxis. 

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2. Fate of arsenate following arsenite oxidation in A grobacterium tumefaciens  GW4: As ^III oxidation and As ^V metabolism

   https://doi.org/10.1111/1462-2920.12465  

   Wang, Qian; Qin, Dong; Zhang, Shengzhe; Wang, Lu; Li, Jingxin; Rensing, Christopher; McDermott, Timothy R.; Wang, Gejiao (June 2015, Environmental Microbiology)
3. Metabolic response of Agrobacterium tumefaciens 5A to arsenite: Altered regulation of metabolic pathways by arsenite

   https://doi.org/10.1111/1462-2920.13615  

   Tokmina-Lukaszewska, Monika; Shi, Zunji; Tripet, Brian; McDermott, Timothy R.; Copié, Valérie; Bothner, Brian; Wang, Gejiao (February 2017, Environmental Microbiology)
4. Involvement of a G Protein Regulatory Circuit in Alternative Oxidase Production in Neurospora crassa

   https://doi.org/10.1534/g3.119.400522  

   Bosnjak, Natasa; Smith, Kristina M.; Asaria, Iman; Lahola-Chomiak, Adrian; Kishore, Nishka; Todd, Andrea T.; Freitag, Michael; Nargang, Frank E. (October 2019, G3: Genes|Genomes|Genetics)

   The Neurospora crassa nuclear aod-1 gene encodes an alternative oxidase that functions in mitochondria. The enzyme provides a branch from the standard electron transport chain by transferring electrons directly from ubiquinol to oxygen. In standard laboratory strains, aod-1 is transcribed at very low levels under normal growth conditions. However, if the standard electron transport chain is disrupted, a od-1 mRNA expression is induced and the AOD1 protein is produced. We previously identified a strain of N. crassa , that produces high levels of aod-1 transcript under non-inducing conditions. Here we have crossed this strain to a standard lab strain and determined the genomic sequences of the parents and several progeny. Analysis of the sequence data and the levels of aod-1 mRNA in uninduced cultures revealed that a frameshift mutation in the flbA gene results in the high uninduced expression of aod-1 . The flbA gene encodes a regulator of G protein signaling that decreases the activity of the Gα subunit of heterotrimeric G proteins. Our data suggest that strains with a functional flbA gene prevent uninduced expression of aod-1 by inactivating a G protein signaling pathway, and that this pathway is activated in cells grown under conditions that induce aod-1 . Induced cells with a deletion of the gene encoding the Gα protein still have a partial increase in aod-1 mRNA levels, suggesting a second pathway for inducing transcription of the gene in N. crassa . We also present evidence that a translational control mechanism prevents production of AOD1 protein in uninduced cultures. 

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5. Bio‐inspired Nonheme Iron Oxidation Catalysis: Involvement of Oxoiron(V) Oxidants in Cleaving Strong C−H Bonds

   https://doi.org/10.1002/anie.201906551  

   Kal, Subhasree; Xu, Shuangning; Que, Jr., Lawrence (March 2020, Angewandte Chemie International Edition)

   Abstract Nonheme iron enzymes generate powerful and versatile oxidants that perform a wide range of oxidation reactions, including the functionalization of inert C−H bonds, which is a major challenge for chemists. The oxidative abilities of these enzymes have inspired bioinorganic chemists to design synthetic models to mimic their ability to perform some of the most difficult oxidation reactions and study the mechanisms of such transformations. Iron‐oxygen intermediates like iron(III)‐hydroperoxo and high‐valent iron‐oxo species have been trapped and identified in investigations of these bio‐inspired catalytic systems, with the latter proposed to be the active oxidant for most of these systems. In this Review, we highlight the recent spectroscopic and mechanistic advances that have shed light on the various pathways that can be accessed by bio‐inspired nonheme iron systems to form the high‐valent iron‐oxo intermediates. 

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