scholarly journals Sequence and Analysis of a Plasmid-Encoded Mercury Resistance Operon from Mycobacterium marinum Identifies MerH, a New Mercuric Ion Transporter

2008 ◽  
Vol 191 (1) ◽  
pp. 439-444 ◽  
Author(s):  
Mathieu Schué ◽  
Lynn G. Dover ◽  
Gurdyal. S. Besra ◽  
Julian Parkhill ◽  
Nigel L. Brown
Keyword(s):  
Escherichia Coli ◽  
Dna Sequence ◽  
Mycobacterium Marinum ◽  
Mercury Resistance ◽  
Cysteine Residues ◽  
Ion Transporter ◽  
Mercuric Reductase ◽  
Mercuric Ion ◽  
Biological Analysis ◽  
Mercuric Ions

ABSTRACT In this study, we report the DNA sequence and biological analysis of a mycobacterial mercury resistance operon encoding a novel Hg2+ transporter. MerH was found to transport mercuric ions in Escherichia coli via a pair of essential cysteine residues but only when coexpressed with the mercuric reductase.

Evidence for direct interactions between the mercuric ion transporter (MerT) and mercuric reductase (MerA) from the Tn501 mer operon

BioMetals ◽  
2007 ◽  
Vol 21 (2) ◽  
pp. 107-116 ◽  
Author(s):  
Mathieu Schue ◽  
Kerry J. Glendinning ◽  
Jon L. Hobman ◽  
Nigel L. Brown
Keyword(s):  
Ion Transporter ◽  
Mer Operon ◽  
Mercuric Reductase ◽  
Mercuric Ion

Mercury transport and resistance

2002 ◽  
Vol 30 (4) ◽  
pp. 715-718 ◽  
Author(s):  
N. L. Brown ◽  
Y.-C. Shih ◽  
C. Leang ◽  
K. J. Glendinning ◽  
J. L. Hobman ◽  
...  
Keyword(s):  
Active Site ◽  
Short Review ◽  
Transport Proteins ◽  
Transport Systems ◽  
Mercury Resistance ◽  
Resistance Proteins ◽  
Mercuric Ion ◽  
Mercury Transport ◽  
Mercuric Ions

Resistance to mercuric ions in bacteria is conferred by mercuric reductase, which reduces Hg(II) to Hg(0) in the cytoplasmic compartment. Specific mercuric ion transport systems exist to take up Hg(II) salts and deliver them to the active site of the reductase. This short review discusses the role of transport proteins in resistance and the mechanism of transfer of Hg(II) between the mercury-resistance proteins.

Enzymatic reduction of mercurous and mercuric ions in Bacillus cereus

1981 ◽  
Vol 27 (2) ◽  
pp. 192-197 ◽  
Author(s):  
K. Izaki
Keyword(s):  
Escherichia Coli ◽  
Bacillus Cereus ◽  
Heavy Metal Ions ◽  
Heat Stability ◽  
Nutrient Broth ◽  
R Factor ◽  
Mercuric Ion ◽  
Enzymatic Reduction ◽  
Mercuric Ions ◽  
Sulfhydryl Compounds

A strain of Bacillus cereus, which can grow in nutrient broth containing 50 μM HgCl2, was isolated from soil. Mercurous or mercuric ion dependent oxidation of reduced NADPH was demonstrated in crude extracts of cells grown in nutrient broth containing 10 μM HgCl2. The properties of this mercuric reductase were similar to those of the enzymes from R factor bearing Escherichia coli in substrate specificity, heat stability, requirement of sulfhydryl compounds, sensitivity to some heavy metal ions, and molelcular weight.

scholarly journals Further tests of a recombination model in which chi removes the RecD subunit from the RecBCD enzyme of Escherichia coli.

Genetics ◽  
1990 ◽  
Vol 126 (3) ◽  
pp. 519-533 ◽  
Author(s):  
F W Stahl ◽  
L C Thomason ◽  
I Siddiqi ◽  
M M Stahl
Keyword(s):  
Escherichia Coli ◽  
Dna Sequence ◽  
Dna Packaging ◽  
Lambda Phage ◽  
Recombination Model ◽  
Phage Types ◽  
Point Of Entry ◽  
Reciprocal Recombination ◽  
Recbcd Enzyme ◽  
Lambda Dna

Abstract When one of two infecting lambda phage types in a replication-blocked cross is chi + and DNA packaging is divorced from the RecBCD-chi interaction, complementary chi-stimulated recombinants are recovered equally in mass lysates only if the chi + parent is in excess in the infecting parental mixture. Otherwise, the chi 0 recombinant is recovered in excess. This observation implies that, along with the chi 0 chromosome, two chi + parent chromosomes are involved in the formation of each chi + recombinant. The trimolecular nature of chi +-stimulated recombination is manifest in recombination between lambda and a plasmid. When lambda recombines with a plasmid via the RecBCD pathway, the resulting chromosome has an enhanced probability of undergoing lambda x lambda recombination in the interval into which the plasmid was incorporated. These two observations support a model in which DNA is degraded by Exo V from cos, the sequence that determines the end of packaged lambda DNA and acts as point of entry for RecBCD enzyme, to chi, the DNA sequence that stimulates the RecBCD enzyme to effect recombination. The model supposes that chi acts by ejecting the RecD subunit from the RecBCD enzyme with two consequences. (1) ExoV activity is blocked leaving a highly recombinagenic, frayed duplex end near chi, and (2) as the enzyme stripped of the RecD subunit travels beyond chi it is competent to catalyze reciprocal recombination.

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