Difference between revisions of "Part:BBa K1420001"

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merA, mercuric reductase from Serratia marcescens

Overview

The essential gene to mercury resistance is merA that encodes a cytoplasmic mercuric ion reductase, MerA. Both MerA and the organomercurial lyase, MerB, works together to detoxify inorganic and organic mercury compound. While MerA and MerB are the key enzymes of mercury detoxification, they orchestrate with mercury transport proteins, MerT and MerP, to confer bacterial mercury resistance. Figure 1 shows the interactions of MerA and other proteins encoded by Mer Operon. MerA and gene merA are highlighted in orange.

This figure is adpated from "Bacterial mercury resistance from atoms to ecosystems". Reference: T. Barkay et al. FEMS Microbiology Reviews 27 (2003) 355-384.

Function

MerA catalyzes the reduction of mercuric ion to the relative inert, volatile monoatomic mercury in a NADPH dependent reaction.

Scheme 1. MerA Catalyzed Reaction

Structure and Mechanism

Characterization of merA

To test the effect of MerA to the level of mercury resistance, we generated a merA deletion mutant and characterized it by zone of inhibition test.

Zone of Inhibition Results

Figure 2. Zones of Inhibition Test For Mercury Resistance Activity. Three different plasmids were expressed in Escherichia coli strain K12 to compare level of mercury resistance. (A)Plates of ZOI test. Left, K12 conntaining pBBRBB::mer; center,K12 containing pBBRBB::gfp; right, K12 strain containing pBBRBB::merΔmerA, or the merA deletion mutant. (b) Graphical representation of the size of zones of inhibition diameter. The diameter of the Zone of Inhibition was measured in triplicate. Green corresponds to pBBRBB::gfp, blue to pBBRBB::mer, and red to pBBRBB::merΔmerA.

Sequence and Features