Results

Fractionation controls and protein expression

Figures 1-3 depict our fractionation controls and blot for the identification of saCas9 protein (expected size ~130 kB). The rightmost column of the blot, labelled "control" is a purified His-tagged protein and was used to ensure that the anti-His antibody could properly bind the protein in question. The fractionation results indicated that although Maltose-binding periplasmic protein (MBP) was exclusively present in the periplasmic fraction, showing strong bands of the expected size (42.5 kDa), GroEl was visible in both the cell's periplasm and cytoplasm (60 kDa) suggesting leakage from the cytoplasm to the periplasm. Although the positive control was successful, there was no evidence of saCas9 in the anti-His6 blot.

To prevent leakage between the two compartments, the current protocol (cold osmotic shock) could be optimized (e.g by minimizing incubation time of the cells on ice and proceeding to the centrifugation step earlier) or alternative protocols could be attempted (e.g. protocols utilizing lysozyme).

Cas9 functionality assay

OMV visualization

Vesicle delivery to Top10 cells - TEM visualization

Achievements