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2 edition of Studies on mercuric reductase and thermophilic mercury resistance found in the catalog.

Studies on mercuric reductase and thermophilic mercury resistance

Kerry Jane Glendinning

Studies on mercuric reductase and thermophilic mercury resistance

by Kerry Jane Glendinning

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Published by University of Birmingham in Birmingham .
Written in English


Edition Notes

Thesis (Ph.D) - University of Birmingham, School of Biological Sciences, Faculty of Science.

Statementby Kerry Jane Glendinning.
ID Numbers
Open LibraryOL18927467M

Mercuric reductase (MerA) is central to the mercury (Hg) resistance (mer) system, catalyzing the reduction of ionic Hg to volatile Hg(0).A total of merA homologues were identified in sequence databases, the majority of which belonged to microbial lineages that occupy oxic was absent among phototrophs and in lineages that inhabit anoxic environments. Abstract. The evolutionary origin of the broadly distributed mer system, which plays an important role in mercury detoxification and biogeochemistry, is presently unknown. The phylum Deinococcus/Thermus was found to be one of the deepest-branching bacterial lineage to have a homolog of merA, which specifies reduction of ionic to elemental mercury, and the mercuric reductase (MerA) of Thermus.

Interaction of Tn mercuric reductase and dihydroflavin adenine dinucleotide anion with metal ions: implications for the mechanism of mercuric reductase mediated mercury(II) reduction. Biochemistry , 31 (4), Mercuric reductase reduces Hg/sup 2 +/ to metallic mercury (Hg/sup 0/). Organomercurial lyases have a molecular weight of 20, to 40,, are composed of 1 or 2 subunits and require the presence of thiol. Plasmic-encoded Hg/sup 2 +/ resistance and mercuric reductase activity have not been detected in many species of bacteria.

This chapter concentrates on selected aspects of microbial mercury reduction and other mechanisms of mercuric ion resistance which are relevant to the interaction of metals and microorganisms in the environment. Mercury (Hg) is simple to refine—the ores are roasted in a current of air, and metallic mercury is condensed from the vapor. The simplicity of refining and the unusual properties of. Mercury resistance mediated by mercuric reductase (MerA) is widespread among bacteria and operates under the control of MerR. MerR represents a unique class of transcription factors that exert both positive and negative regulation on gene expression. Archaea and bacteria are prokaryotes, yet little is known about the biological role of mercury in archaea or whether a resistance mechanism.


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Studies on mercuric reductase and thermophilic mercury resistance by Kerry Jane Glendinning Download PDF EPUB FB2

Mercury (Hg) resistance (mer) by the reduction of mercuric to elemental Hg is broadly distributed among the Bacteria and Archaea and plays an important role in Hg detoxification and biogeochemical is the protein subunit of the homodimeric mercuric reductase (MR) enzyme, the central function of the mer system.

MerA sequences in the phylum Aquificae form the deepest-branching Cited by: Mercury(II) reductase (EC ), commonly known as MerA, is an oxidoreductase enzyme and flavoprotein that catalyzes the reduction of Hg 2+ to Hg y(II) reductase is found in the cytoplasm of many eubacteria in both aerobic and anaerobic environments and serves to convert toxic mercury ions into relatively inert elemental mercuryBRENDA: BRENDA entry.

Mercuric ion reductase (MerA), a mercury detoxification enzyme, has been tuned by evolution to have high specificity for mercuric ions (Hg 2+) and to catalyze their reduction to a more volatile, less toxic elemental form.

Here, we present a biochemical and structural characterization of MerA from the thermophilic crenarchaeon Metallosphaera by: 4.

Mercury Resistance and Mercuric Reductase Activities and Expression among Chemotrophic Thermophilic Aquificae Zachary Freedman,a,b* Chengsheng Zhu,a and Tamar Barkaya,b Mercury Resistance among Aquificae September Volume 78 Number 18 on Aug by guest Cited by: Mercuric reductase (MerA) is central to the mercury (Hg) resistance (mer) system, catalyzing the reduction of ionic Hg to volatile Hg(0).A total of merA homologues were identified in sequence databases, the majority of which belonged to microbial lineages that occupy oxic was absent among phototrophs and in lineages that inhabit anoxic by:   The heart of mer-mediated mercury resistance is mercuric ion reductase (MerA), which catalyzes the conversion of thiol-avid Hg 2+ to volatile Hg 0, which lacks significant affinity with any other ligand of functional enzyme is energy dependent in the form of NADPH and is found in the cytoplasm.

However, in some bacterial isolates they have been reported for their resistance towards. FEMS Microbiology Letters 19 () 93 Published by Elsevier Mercuric reductase activity in a mercury-resistant strain of Yersinia en terocolitica M.

Blaghen, Marie-Claire Lett and D.J-M. Vidon Laboratoire de Bact&iologie, Facultb de Pharmacie, Universitb Louis Pasteur, BP 10, Strasbourg Cedex, France Received 8 March Accepted 15 March 1.

Mercury is a redox-active heavy metal that reacts with active thiols and depletes cellular antioxidants. Active resistance to the mercuric ion is a widely distributed trait among bacteria and results from the action of mercuric reductase (MerA).

Protein phylogenetic analysis of MerA in bacteria indicated the occurrence of a second distinctive form of MerA among the archaea, which lacked an N. Explore the latest full-text research PDFs, articles, conference papers, preprints and more on MERCURY RESISTANT BACTERIA.

Find methods information, sources, references or conduct a literature. The central enzyme in the microbial mercury detoxification system is the mercuric reductase (MerA) protein, which catalyzes the reduction of Hg(II) to volatile Hg(0).

In addition to MerA, mer operons encode for proteins involved in regulation, Hg binding, and organomercury degradation.

Mer-mediated approaches have had broad applications in the. INTRODUCTION. Bacterial mercury (Hg) resistance genes (mer) are important drivers in the biogeochemical cycle of operons catalyze the conversion of inorganic mercury [Hg(II)] and sometimes methylmercury (MeHg) to elemental mercury [Hg(0)] ().MeHg, which is more toxic than Hg(II) or Hg(0), is the form that biomagnifies in aquatic food webs (2, 3) and can cause toxicity to humans.

Active resistance to the mercuric ion is a widely distributed trait among bacteria and results from the action of mercuric reductase (MerA). Protein phylogenetic analysis of MerA in bacteria indicated the occurrence of a second distinctive form of MerA among the archaea, which lacked an N-terminal metal recruitment domain and a C-terminal.

The new clone, pYW33, expressed broad-spectrum mercury resistance both in Escherichia coli and in Bacillus subtilis, but only in B. subtilis was the mercuric reductase activity inducible. According to existing data, mercury resistance operons (mer operons) are in general thought to be rare in bacteria, other than those from mercury-contaminated have found that a high proportion of strains in environmental isolates of Gram-positive bacteria express mercuric reductase (MerA protein): the majority of these strains are apparently sensitive to mercury.

Smith, D. () R-factors mediate resistance to mercury, nickel and cobalt. ScienceSummers, A. () Organization, expression and evolu- tion of genes for mercury resistance. Annual Review of Microbiol Summers, A.

and Silver, S. () Mercury resistance in a plasmid bearing strain of Escherichia coli. Mercuric ion reductase (MerA), a mercury detoxification enzyme, has been tuned by evolution to have high specificity for mercuric ions (Hg2+) and to catalyze their reduction to a more volatile, less toxic elemental form.

Here, we present a biochemical and structural characterization of MerA from the thermophilic crenarchaeon Metallosphaera sedula. MerA from M.

sedula is a thermostable enzyme. The lower convective layer (LCL) of the Atlantis II brine pool of the Red Sea is a unique environment in terms of high salinity, temperature, and high concentrations of heavy metals. Mercuric reductase enzymes functional in such extreme conditions could be considered a potential tool in the environmental detoxification of mercurial poisoning and might alleviate ecological hazards in the mining.

The current study was aimed at isolating and identifying the halophilic and halotolerant bacteria which can produce mercuric reductase in Gavkhuni wetland in Iran. Moreover, tracking and sequencing merA gene and kinetic properties of mercuric reductase in the selected strain were performed in this study.

Soil samples were taken from Gavkhuni wetland and cultured in nutrient agar medium with 5%. Tn21 encodes mercuric ion resistance (Hg r) and contains the class I integron In2, encoding resistance to sulfonamides (sul) and streptomycin-spectinomycin (aadA) (9, 18).It is carried by the conjugative plasmid NR1 (R), which was isolated in Japan in the s ().More recently, Tn21 and other Tnlike transposons carrying integron-associated antibiotic resistance have been detected in.

A thermophilic bacterial origin and subsequent constraints by redox, light and salinity on the evolution of the microbial mercuric reductase. Environmental Microbiology12 (11), DOI: /jx. Mercury resistance determinants are widespread in Gram-negative bacteria, but vary in the number and identity of genes present.

We have shown that the merF gene from plasmid pMER/ encodes a kDa mercury transport protein, by determining in vivo mercury volatilisation when MerF is expressed in the presence of mercuric reductase.

We have confirmed that MerC of Tn21 is also a mercuric. Mercury (Hg), the environmental toxicant, is present in the soil, water, and air as it is substantially distributed throughout the environment.

Being extremely toxic even at low concentration, its remediation is utterly important. Therefore, it is necessary to detoxify the contaminant within the acceptable limits before threatening the environment.

Although various conventional methods are. Mercury rich geothermal springs are likely environments where mercury resistance is critical to microbial life and where microbe-mercury interactions may have evolved. Eleven facultative thermophilic and chemolithoautotrophic, thiosulfate oxidizing bacteria were isolated from thiosulfate enrichments of biofilms from mercury rich hot sulfidic.