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MerB is a cytoplasmic enzyme that cleaves carbon-mercury bonds in organomercurials
"MerB is located in the cytoplasm of the bacterial cell. It lacks any signal peptide or membrane-spanning domains, and it contains no disulfide bonds, consistent with a cytosolic enzyme that functions in the reducing environment of the cytosol."
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MerB uses essential cysteine residues for catalysis
"Two cysteine residues (conserved as Cys96 and Cys159 in E. coli MerB numbering) are essential for catalysis, forming a bis-thiolated Hg^2+ intermediate and likely delivering the proton to the bound organic group."
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MerB has a unique protein fold specific to mercury resistance
"MerB is a single-domain enzyme with a unique protein fold not found in other protein families. Solution NMR and crystal structure studies revealed that MerB consists of three small β-sheets surrounded by six α-helices, forming a compact globular protein."
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MerB expression is tightly regulated by MerR in response to mercury
"The merB gene in P. aeruginosa is typically co-transcribed as part of the mer operon, under the control of the MerR regulatory protein. When Hg^2+ is present, MerR binds the ion and undergoes a conformational change that activates transcription of the operon."
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MerB enables bioremediation of mercury-contaminated environments
"mercury-resistant pseudomonads with MerB can thrive in mercury-polluted soils, waters, or industrial effluents where they degrade organomercurials that would otherwise accumulate in the food chain. MerB-possessing bacteria have been explored as agents of bioremediation for mercury pollution."