Difference between revisions of "Part:BBa K3189013"

Latest revision as of 03:59, 22 October 2019

Lac-regulated VioABE

Type IIS Compatible Lac-regulated VioABE

vioABE are genes that belong to the first part of the violacein biosynthesis pathway. On their own they produce pro deoxy violacein which is a green pigment. Cells containing BBa_K3189013 on LB + IPTG + ampicillin, when grown in a lawn, they did not produce any clearly visible green pigment (Figure 1a), even after a day of growth at 37 °C and several days of incubation at 4 °C. We hypothesized that the cells could have lost the plasmid containing vioABE so to test this we streaked to isolation from these plates onto a fresh set of LB agar plates with 0.75 mM IPTG, incubated them at 37 °C for a day, and then placed them at 4 °C. After 1 week, a dark green colour became visible (Figure 1b), but only in isolated colonies and at the edges of lawn-like growth indicating the colonies growing in the lawn had not lost the plasmid and some other mechanism was inhibiting pigment production. This however does show that under the right conditions VioABE can be produced and thus create their characteristic green pigment.


Figure 1: E. coli BBa_K3189013 transformants spread on LB agar with 1 mM IPTG. The same plate has much more colour after 7 days in the fridge (right), compared to after 1 day (left). Colour is also more apparent in isolated colonies and at the edges of densely populated areas of growth


Figure 2: Left: E. coli BL21(DE3) BBa_K3189013 cells grown on LB+IPTG+ampicillin. A lawn grew and no colour is visible. Right: The same cells streaked to isolation on a fresh plate, after growth at 37 °C for 1 day and incubation at 4 °C for 4 weeks. Isolated colonies and the edge of lawn-like growths display a very dark pigmentation. The same pattern was seen for all concentrations of IPTG.

Sequence and Features