Organomercurials removal by heterogeneous merB genes harboring bacterial strains.

Organomercury lyase (MerB) is a key enzyme in bacterial detoxification and bioremediation of organomercurials. However, the merB gene is often considered as an ancillary component of the mer operon because there is zero to three merB genes in different mer operons identified so far. In this study, organomercurials' removal abilities of native mercury-resistant bacteria that have one or multiple merB genes were examined. Each heterogeneous merB genes from these bacteria was further cloned into Escherichia coli to investigate the substrate specificity of each MerB enzyme. The merB1 gene from Bacillus megaterium MB1 conferred the highest volatilization ability to methylmercury chloride, ethylmercury chloride, thimerosal and p-chloromercuribenzoate, while the merB3 from B. megaterium MB1 conferred the fastest mercury volatilization activity to p-chloromercuribenzoate. The substrate specificities among these MerB enzymes show the necessity for selecting the appropriate bacteria strains or MerB enzymes to apply them in bioremediation engineering for cleaning up specific organomercurial contaminations.

[1]  G. Endo,et al.  Identification of three merB genes and characterization of a broad-spectrum mercury resistance module encoded by a class II transposon of Bacillus megaterium strain MB1. , 1999, Gene.

[2]  G. Endo,et al.  Structure analysis of a class II transposon encoding the mercury resistance of the Gram-positive Bacterium bacillus megaterium MB1, a strain isolated from minamata bay, Japan. , 1999, Gene.

[3]  G. Endo,et al.  Simultaneous detection and removal of organomercurial compounds by using the genetic expression system of an organomercury lyase from the transposon TnMERI1 , 2002, Applied Microbiology and Biotechnology.

[4]  C. Walsh,et al.  Mechanistic studies of a protonolytic organomercurial cleaving enzyme: bacterial organomercurial lyase. , 1986, Biochemistry.

[5]  J. Omichinski,et al.  Crystal Structures of the Organomercurial Lyase MerB in Its Free and Mercury-bound Forms , 2009, Journal of Biological Chemistry.

[6]  G. Parkin,et al.  Cleaving Mercury-Alkyl Bonds: A Functional Model for Mercury Detoxification by MerB , 2007, Science.

[7]  Susan M. Miller,et al.  Bacterial mercury resistance from atoms to ecosystems. , 2003, FEMS microbiology reviews.

[8]  M. Kiyono,et al.  The merG Gene Product Is Involved in Phenylmercury Resistance in Pseudomonas Strain K-62 , 1999, Journal of bacteriology.

[9]  K. Tonomura,et al.  Purification and Properties of an Enzyme Catalyzing the Splitting of Carbon-Mercury Linkages from Mercury-Resistand Pseudomonas K-62 Strain , 1976 .

[10]  J. Omichinski,et al.  NMR structural studies reveal a novel protein fold for MerB, the organomercurial lyase involved in the bacterial mercury resistance system. , 2004, Biochemistry.

[11]  M. Kiyono,et al.  Nucleotide sequence and expression of the organomercurial-resistance determinants from a Pseudomonas K-62 plasmid pMR26. , 1997, Gene.

[12]  N. Brown,et al.  Horizontal spread of mer operons among gram-positive bacteria in natural environments. , 1998, Microbiology.

[13]  M. Harada,et al.  Minamata disease: methylmercury poisoning in Japan caused by environmental pollution. , 1995, Critical reviews in toxicology.

[14]  J. Hobman,et al.  Class II broad-spectrum mercury resistance transposons in Gram-positive bacteria from natural environments. , 2001, Research in microbiology.

[15]  J. Omichinski,et al.  A stable mercury-containing complex of the organomercurial lyase MerB: catalysis, product release, and direct transfer to MerA. , 2004, Biochemistry.

[16]  S. Lin-Shiau,et al.  Distinct genotoxicity of phenylmercury acetate in human lymphocytes as compared with other mercury compounds. , 1997, Mutation research.

[17]  Keith E Pitts,et al.  The roles of thiols in the bacterial organomercurial lyase (MerB). , 2002, Biochemistry.

[18]  S. Silver,et al.  Nucleotide sequence and expression of the mercurial-resistance operon from Staphylococcus aureus plasmid pI258. , 1987, Proceedings of the National Academy of Sciences of the United States of America.