Coding

Part:BBa_K1509000:Design

Designed by: Tong Li   Group: iGEM14_NEFU_China   (2014-09-26)
Revision as of 12:17, 1 October 2014 by ErinLiu (Talk | contribs) (→‎Source)


Coding for the trans-acting regulator SmtB


Assembly Compatibility:
  • 10
    INCOMPATIBLE WITH RFC[10]
    Illegal PstI site found at 349
  • 12
    INCOMPATIBLE WITH RFC[12]
    Illegal NheI site found at 260
    Illegal PstI site found at 349
  • 21
    COMPATIBLE WITH RFC[21]
  • 23
    INCOMPATIBLE WITH RFC[23]
    Illegal PstI site found at 349
  • 25
    INCOMPATIBLE WITH RFC[25]
    Illegal PstI site found at 349
  • 1000
    COMPATIBLE WITH RFC[1000]


Design Notes

According to the mechanisms of smt locus represented above, gene smtB should function with the accompany of smt operator-promoter. Previous cases selected smtA whose product functions by encoding MT-like to sequester metal ions, while our case intended to take advantage of the trigger lies in this locus. By imitating former researches, in which a promoter less lacZ gene was fused upstream of smtA, we respectively splice two selected reporter genes and sequence from smt operator-promoter to smtB, equivalent to replacing smtA with reporter genes, to visualize the effects of metal ions on the locus.


Source

Metallothioneins(MTs), discovered in horse kidney in 1957 by Margoshes and Vallee are identified as low-molecular weight and sulphydryl rich proteins which bind metal ions in metal-thiolate clusters and whose synthesis increases in response to elevated concentrations of certain metals. In 1988, Olafson and co-workers reported the amino acid sequence of a metal-associated protein isolated from cyanobacterium Synechococcus sp.. With the function of binding metal ions remaining, it only has less than 20% homology in amino acid sequence with known MTs in eukaryotes and thus we call it class II MT or on some occasions MT-like. Owing to the works of Robinson and Huckle, the corresponding locus of Synechococcus PCC7942, smt locus was isolated and analyzed. It includes smtA which encodes the class II MT and a divergently transcribed gene smtB which encodes a trans-acting, autoregulatory repressor that exerts metal ion-inducible negative control over smtA transcription. Between them lies a 100-bp operator-promoter region(smt O-P, BBa_K1509001), which is responsible for the divergent orientation of smtA and smtB.

References