Cadmium is a non essential trace metal, the increasing amount of which can be detrimental to the health. Once the cadmium level is elevated in the blood, it remains high even when its source is depleted. There is a need to remove the metal from the environment so our food, air or water is not contaminated by it. Metallothioneins (MTs) are metal binding proteins that are rich in cysteine residues constituting 30% of the total protein. The thiol groups bind to the metal ions. Different organisms such as bacteria, protozoa and mammals like humans have shown increased production of MTs with...

Copper is an essential trace metal for both prokaryotes and eukaryotes, and is associated with various metal enzymes which play many essential roles in the living system. But excess of the metal is very toxic and even lethal for living organisms. In microorganisms the intracellular level of copper is maintained by many genes working as an operon and induced by the presence of copper in their environment. One such operon is called cus operon regulated by cusRS two component system in Klebsiella pneumoniae. This cusS (sensory region) and cusR (regulatory region) autoregulate the expression of...

Transition metals affect the viability of organisms and are fundamental and limiting factors at the same time, since they represent nutritionally important yet cytotoxic components in our environment. Both prokaryotes and eukaryotes carry cellular systems to maintain the metal homeostasis.Metallothioneins (MTs) are 6-7 kDa, ubiquitous, cytoplasmic, cysteine rich proteins, which have the capacity of high affinity binding to heavy metal ions. MTs play key role in essential as well as toxic heavy metal metabolism in the organisms. The ciliates tolerate elevated concentrations of metals, which...

First cadmium metallothionein like gene (PMCd1) from a ciliate, Paramecium sp. and a novel cadmium inducible metallothionein (TMCd1) gene has been identified and sequenced from the locally isolated ciliate; Tetrahymena tropicalis lahorensis isolated from industrial wastewater. Both the genes (PMCd1 and TMCd1) are intronless, encoding 612 and 471 nucleotides respectively, with TGA as the stop codon and TAA coding for glutamine. The coding region of PMCd1 comprises 203 amino acids, including 37 cysteine residues with a conserved structural pattern arranged in 17 cys-x-y-cys, 1 cys-cys and cys...