Operon mer: bacterial resistance to mercury and potential for bioremediation of contaminated environments
Genet. mol. res. (Online)
;
2(1): 92-101, Mar. 2003.
Artículo
en Inglés
| LILACS
| ID: lil-417621
RESUMO
Mercury is present in the environment as a result of natural processes and from anthropogenic sources. The amount of mercury mobilized and released into the biosphere has increased since the beginning of the industrial age. Generally, mercury accumulates upwards through aquatic food chains, so that organisms at higher trophic levels have higher mercury concentrations. Some bacteria are able to resist heavy metal contamination through chemical transformation by reduction, oxidation, methylation and demethylation. One of the best understood biological systems for detoxifying organometallic or inorganic compounds involves the mer operon. The mer determinants, RTPCDAB, in these bacteria are often located in plasmids or transposons and can also be found in chromosomes. There are two classes of mercury resistance narrow-spectrum specifies resistance to inorganic mercury, while broad-spectrum includes resistance to organomercurials, encoded by the gene merB. The regulatory gene merR is transcribed from a promoter that is divergently oriented from the promoter for the other mer genes. MerR regulates the expression of the structural genes of the operon in both a positive and a negative fashion. Resistance is due to Hg2+ being taken up into the cell and delivered to the NADPH-dependent flavoenzyme mercuric reductase, which catalyzes the two-electron reduction of Hg2+ to volatile, low-toxicity Hg0. The potential for bioremediation applications of the microbial mer operon has been long recognized; consequently, Escherichia coli and other wild and genetically engineered organisms for the bioremediation of Hg2+-contaminated environments have been assayed by several laboratories
Texto completo:
Disponible
Índice:
LILACS (Américas)
Asunto principal:
Operón
/
Bacterias
/
Contaminantes Ambientales
/
Mercurio
Idioma:
Inglés
Revista:
Genet. mol. res. (Online)
Asunto de la revista:
Biologia Molecular
/
Genética
Año:
2003
Tipo del documento:
Artículo
País de afiliación:
Brasil
Institución/País de afiliación:
Universidade Federal de Minas Gerais/BR
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