Functional Dissection of a Mercuric Ion Transporter, MerC, from<i>Acidithiobacillus ferrooxidans</i>

Sasaki, Yoshito; Minakawa, Takahiro; Miyazaki, Atushi; Silver, Simón; Kusano, Tomonobu

doi:10.1271/bbb.69.1394

Cited by 38 publications

(14 citation statements)

References 31 publications

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“…In the past few years, the model eukaryotic cell Saccharomyces cerevisiae has been used to identify several cation transporters that sequester heavy metals into inactive organelles (Malik 2004). Sasaki et al (2005) reported that the membrane-bound mercury transporter MerC, which is encoded by the merC gene of Tn21, can recognize and transport cadmium in addition to mercury into E. coli cells.…”

Section: Discussionmentioning

confidence: 99%

“…Whereas most other resistance systems employ cation efflux-type transporters, the mer determinants carry influx-type transporters (Silver and Phung 1996). A bacterial heavy metal transporter, MerC, which was isolated from the mer operon and was localized to the inner membrane, can independently recognize and transport mercury in addition to cadmium (Kusano et al 1990;Sahlman et al 1997Sahlman et al , 1999Sasaki et al 2005). Furthermore, we recently reported that MerC, which was isolated from the Tn21-encoded mer operon, localized to the inner membrane of transgenic yeast and enhanced cadmium accumulation from Cd-contaminated medium (Kiyono et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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Expression of the bacterial heavy metal transporter MerC fused with a plant SNARE, SYP121, in Arabidopsis thaliana increases cadmium accumulation and tolerance

Kiyono

Oka

Sone

et al. 2011

Planta

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The bacterial merC gene from the Tn21-encoded mer operon is a potential molecular tool for improving the efficiency of metal phytoremediation. Arabidopsis SNARE molecules, including SYP111, SYP121, and AtVAM3 (SYP22), were attached to the C-terminus of MerC to target the protein to various organelles. The subcellular localization of transiently expressed GFP-fused MerC-SYP111, MerC-SYP121, and MerC-AtVAM3 was examined in Arabidopsis suspension-cultured cells. We found that GFP-MerC-SYP111 and GFP-MerC-SYP121 localized to the plasma membrane, whereas GFP-AtVAM3 localized to the vacuolar membranes. These results demonstrate that SYP111/SYP121 and AtVAM3 target foreign molecules to the plasma membrane and vacuolar membrane, respectively. To enhance the efficiency and potential of plants to sequester and accumulate cadmium from contaminated sites, transgenic Arabidopsis plants expressing MerC, MerC-SYP111, MerC-SYP121, or MerC-AtVAM3 were generated. The transgenic plants that expressed MerC, MerC-SYP121, or MerC-AtVAM3 appeared to be normal, whereas the transgenic that expressed MerC-SYP111 exhibited severe growth defects. The transgenic plants expressing merC-SYP121 were more resistant to cadmium than the wild type and accumulated significantly more cadmium. Thus, the expression of MerC-SYP121 in the plant plasma membrane may provide an ecologically compatible approach for the phytoremediation of cadmium pollution.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Expression of the bacterial heavy metal transporter MerC fused with a plant SNARE, SYP121, in Arabidopsis thaliana increases cadmium accumulation and tolerance

Kiyono

Oka

Sone

et al. 2011

Planta

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“…We recently discovered that E. coli cells expressing the merC gene from A. ferrooxidans became hypersensitive to both HgCl 2 and CdCl 2 (Sasaki et al 2005). This suggested that this mercury transporter can recognize and transport Cd 2+ in addition to Hg 2+ .…”

Section: Discussionmentioning

confidence: 99%

“…Since we found that E. coli cells expressing the Acidithiobacillus merC gene were hypersensitive not only to HgCl 2 but also to CdCl 2 (Sasaki et al 2005), we evaluated both the HgCl 2 -and CdCl 2 -sensitivity of the Arabidopsis merC-transformants. Thus, seeds (T 4 generation) of the homozygous lines 74 and 77 were germinated and grown on half strength MS 0.8% agar media containing 1% sucrose for 7 days.…”

Section: Mercury Uptake By Merc-overexpressing Arabidopsismentioning

confidence: 99%

Generation of Mercury-Hyperaccumulating Plants through Transgenic Expression of the Bacterial Mercury Membrane Transport Protein MerC

Sasaki

Hayakawa²,

Inoue

et al. 2006

Transgenic Res

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The merC gene from Acidithiobacillus ferrooxidans functions as a mercury uptake pump. MerC protein localizes in the cytoplasmic membrane of plant cells. When Arabidopsis thaliana and tobacco plants were transformed with the merC gene under the control of the Cauliflower mosaic virus 35S promoter, the resulting overexpression of merC rendered the host plants hypersensitive to Hg2+ and they accumulated approximately twice as much Hg2+ ion as the wild type plants. Thus, bacterial mercuric ion transporters such as MerC may be useful molecular tools for producing transgenic plants that hyperaccumulate Hg2+ ion.

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“…9) An example of such a method is the use of transgenic plants expressing bacterial heavy metal transporters such as MerC to improve the uptake and transport of metals. 10,11) Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are membrane-associated proteins that serve as molecular tools for targeting foreign molecules to specific membranes in plants. In a previous study, genetically engineered Arabidopsis plants were obtained by fusing bacterial merC gene to genes encoding plant SNAREs, and the resultant plants were able to express MerC in specific membranes.…”

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confidence: 99%

A Novel Role of MerC in Methylmercury Transport and Phytoremediation of Methylmercury Contamination

Sone

Uraguchi

Takanezawa

et al. 2017

Biological & Pharmaceutical Bulletin

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MerC, encoded by merC in the transposon Tn21 mer operon, is a heavy metal transporter with potential applications for phytoremediation of heavy metals such as mercuric ion and cadmium. In this study, we demonstrate that MerC also acts as a transporter for methylmercury. When MerC was expressed in Escherichia coli XL1-Blue, cells became hypersensitive to CH 3 Hg(I) and the uptake of CH 3 Hg(I) by these cells was higher than that by cells of the isogenic strain. Moreover, transgenic Arabidopsis plants expressing bacterial MerC or MerC fused to plant soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) accumulated CH 3 Hg(I) effectively and their growth was comparable to the wild-type plants. These results demonstrate that when the bacterium-derived merC gene is ectopically introduced in genetically modified plants, MerC expression in the transgenic plants promotes the transport and sequestration of methylmercury. Thus, our results show that the expression of merC in Arabidopsis results in transgenic plants that could be used for the phytoremediation and elimination of toxic methylmercury from the environment.Key words MerC; methylmercury; phytoremediation; bacterial broad-spectrum mercury transporter Mercury pollution occurring as a result of anthropogenic activities, such as waste production and increased use of industrial, medicinal, and artisanal products containing mercury is a global problem.1-5) Mercury and its organic derivatives such as methylmercury are acutely toxic to humans. Hence, the removal of mercurials from the environment remains an ongoing challenge.Phytoremediation is a method for detoxifying metal-contaminated soils, waste, and sediment using green plants. This method is cost-effective, sustainable, and environmentally safe for a wide range of contaminated sites, [6][7][8] but is timeconsuming. Strategies that rely on biological functions might prove to be faster and more effective.9) An example of such a method is the use of transgenic plants expressing bacterial heavy metal transporters such as MerC to improve the uptake and transport of metals. 10,11) Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are membrane-associated proteins that serve as molecular tools for targeting foreign molecules to specific membranes in plants. In a previous study, genetically engineered Arabidopsis plants were obtained by fusing bacterial merC gene to genes encoding plant SNAREs, and the resultant plants were able to express MerC in specific membranes. The fusion of merC to SYP121 results in a fusion protein that can be expressed on the plasma membrane, while fusing merC to AtVAM3 enables the fusion protein to be expressed on vacuolar membranes.12) The expression of MerC-SYP121 in genetically engineered Saccharomyces or Arabidopsis resulted in significant accumulation of Cd(II) 12,13) and Hg(II) 14,15) as well as in the protection of the organism from metal-induced toxicity.Removal of methylmercury from the environment is important because inorganic me...

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Functional Dissection of a Mercuric Ion Transporter, MerC, fromAcidithiobacillus ferrooxidans

Cited by 38 publications

References 31 publications

Expression of the bacterial heavy metal transporter MerC fused with a plant SNARE, SYP121, in Arabidopsis thaliana increases cadmium accumulation and tolerance

Expression of the bacterial heavy metal transporter MerC fused with a plant SNARE, SYP121, in Arabidopsis thaliana increases cadmium accumulation and tolerance

Generation of Mercury-Hyperaccumulating Plants through Transgenic Expression of the Bacterial Mercury Membrane Transport Protein MerC

A Novel Role of MerC in Methylmercury Transport and Phytoremediation of Methylmercury Contamination

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