Microbial metallothioneins

doi:10.1016/S0065-2911(01)44014-8

Advances in Microbial Physiology

Volume 44, 2001, Pages 183-213

https://doi.org/10.1016/S0065-2911(01)44014-8 Get rights and content

Abstract

Bacterial metal lothioneins bind, sequester and buffer excess intracellular zinc. At present, the vast majority of the available experimental data relate to cyanobacterial metallothionein, SmtA, from Synechococcus PCC 7942. SmtA is required for normal resistance to zinc and smtA-mediated zinc resistance has been used as a selectable marker. The imidazole groups of histidine residues, in addition to the thiol groups of cysteine residues, co-ordinate zinc in bacterial metal lothioneins. The structure of bacterial metallothionein must facilitate some discrimination between ‘adventitious’ and ‘adventageous’ zinc-binding sites such that under excess zinc conditions metal is predominantly scavenged from the former. It remains unclear whether or not bacterial metallothionein also acts as a zinc store that supplies zinc-requiring proteins or if under some conditions it deactivates a subset of proteins via zinc removal.

Expression of smtA is induced in response to elevated concentrations of zinc via the action of SmtB. SmtB has some sequence similarity to the arsenic responsive repressor ArsR and genes encoding related proteins are present in many bacterial genomes. Metal perception by SmtB differs from ArsR. The latter contains a characteristic Cys-Val-Cys motif associated with a DNA-binding helixturn-helix (the ArsR motif), while the former contains metal-binding motifs associated with a carboxyl-terminal α-helix that forms the interface between SmtB dimers (the SmtB motif). Some SmtB-ArsR family proteins, including the zinc sensor ZiaR from the cyanobacterium Synechocystis PCC 6803, have the metal-sensory motifs of both SmtB and ArsR. The mechanisms of action, and the features that allow discrimination between different metal ions by these sensors, are discussed.

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Microbial metallothioneins

Abstract

J. Biol. Cheat.

J. Biol. Cheat.

J. Mot. Biol.

J. Biol. Chem.

J. Biol. Cheat.

J. Biol. Chem.

J. Biol. Chem.

Methods Enzymol.

J. Biol. Chem.

Gene

J. Mol. Biol.

Structure

J. Biol. Chem.

FEBS Lett.

J. Biol. Chem.

J. Biol. Chem.

J. Biol. Chem.

J. Biol. Chem.

Curr. Opin. Chem. Biol.

J. Biol. Chem.

J. Biol. Chem.

J. Mol. Biol.

A possible mechanism for metal-ion induced DNA-protein dissociation in a family of prokaryotic transcription factors

Nucleic Acids Res.

Amplification of the metallothionein-I gene in cadmium-resistant mouse cells

Cloning, chromosomal mapping and characterization of the human metal-regulatory transcription factor MTF-1

Nucleic Acids Res.

MRE-binding transcription factor- I : weak zinc-binding finger domains 5 and 6 modulate the structure, affinity and specificity of the metal-response element complex

Biochemistry

Co-crystal structure of the HNF3/fork head DNA-recognition motif resembles histone H5

Nature

Crystal structure of the cyanobacterial metallothionein repressor SmtB: a model for metalloregulatory proteins

J. Mol. Biol.

Co-ordinate amplification of metallothionein I and II genes in cadmium-resistant Chinese hamster cells: implications for mechanisms regulating metallothionein gene expression

Mol. Cell. Biol.

CadC, the transcriptional regulatory protein of the cadmium resistance system of Staphylococcus aureus plasmid pI258

J. Bacteriol.

Metalloregulation of the cyanobacterial smt locus: identification of SmtB binding sites and direct interaction with metals

Nucleic Acids Res.

Tandem gene amplification mediates copper resistance in yeast

Zinc: Lewis acid catalysis and regulation

Evolutionary relationships among cyanobacteria and green chloroplasts

J. Bacteriol.

Embryonic lethality and liver degeneration in mice lacking the metal-responsive transcriptional activator MTF-1

EMBO J.

Amplification and rearrangement of a prokaryotic metallothionein locus smt in Synechococcus PCC 6301 selected for tolerance to cadmium

Deletion within the metallothionein locus of Cd-tolerant Synechococcus PCC 6301 involving a highly iterated palindrome (HIP1 )

Mol. Microbial.

Metal lothionein

Ann. Rev. Biochem.