Difference between revisions of "Part:BBa K190019"

Revision as of 15:52, 21 October 2009

fMT

[http://2009.igem.org/Team:Groningen/Project/Accumulation#fMT fMT] is a metallothionein, binding Arsenite(III) and Arsenate(V), it has higher affinity for As(III). The protein was isolated from [http://en.wikipedia.org/wiki/Fucus_vesiculosus Fucus vesiculosus] and described by Morris et al. It consists of 67 amino acid residues and has 16 cysteine residues, a high cysteine content is a key feature of MT. Another characteristic is the lack of aromatic residues is also seen in fMT where it only has one, tryptophan. Two domains containing cysteine residues are presumed to be involved in the metal binding function. Unusual in fMT is the presence of a 14 amino acid linker region between the two putative metal-binding domains which contains no cysteine residues.

Usage and Biology

Overexpression of fMT can be used to accumulate Arsenic without toxification of the cells. The gene was functionally expressed in E. coli.

From literature it is known that metallothioneins are degraded inside lysozymes, especially when they are in the apo- (non-bound) state (Gold 2008), for bacteria this is not known, but from mammalian MT this can be estimated up to 0.8nmol apo-MT/mg protein/min (Klaassen 1994). This can be avoided by adding ~0.5mM metal-salts (ZnCl2, CuSO4) to cells expressing the protein. But afterwards the metals should be chelated from the metallothioneins by for instance EDTA.

Sequence and Features