Difference between revisions of "Part:BBa K1758377"

The plant pathogen Agrobacterium tumefaciens has been widely used in plant research, as it can transform plant cells with the help of the Ti-plasmid (tumor-inducing plasmid). A. tumefaciens is able to utilize the uncommon carbon and energy source γ-butyrolactone (GBL) found in plants. To do this, the bacterium uses the enzymes of the blcABC operon (Chai et al. 2007). This operon is localized on the second megaplasmid of A. tumefaciens C58 strain, pAtC58. blcABC expression is controlled by the repressor protein BlcR . When GBL is not present, two dimers of BlcR form a tetramer and inhibit operon expression by binding to an operator sequence localized in front of the operon, thereby hindering the polymerase from transcribing the DNA (Pan et al. 2011, 2013). The inhibition of operon repression was shown to be inducible not only by GBL, but even stronger by GHB (gamma-hydroxybutyrate) and SSA (succinic semialdehyde) (Chai et al. 2007).

The enzymes coded for in the blcABC operon catalyze the reaction of GHB to GBL in a first step. If GBL is taken up by an organism containing the operon, it is processed to GHB that even stronger induces the operon. Further, GHB is processed to succinic semialdehyde that finally enters the GABA pathway. Therefore, the operon enables the chassis to utilize GHB or GBL as carbon and nitrogen source. It has been shown that the transformation of the operon enables E. coli to grow on GBL as sole carbon source. (Carlier et al. 2004). Hence, as further experiments, the induction might be increased by the additional transformation of the operon containing blcA.