A cell self-disruption system that produces the desired protein
followed by the co-expression of two lysis genes was established
using E. coli harboring two compatible plasmids. The two lysis
genes are DAAO and T7 lysozyme. Expression of T7 lysozyme
alone did not induce cell lysis because the enzyme is unable to
penetrate the cytoplasmic membrane of E. coli cells to its substrate
in the peptidoglycan layer. On the other hand, expression
of DAAO alone weakened the cell strength and resulted in an
appreciable E. coli cells lysis, which enable release of a portion
of target protein GFP. With T7 lysozyme co-expressed with
DAAO, significant cell lysis and release of GFP were observed.
Evidently, the co-expressed T7 lysozyme helped DAAO to disrupt
the cell wall. The synergetic effect on cell self-disruption
made an efficient target intracellular protein release to the culture
medium possible.
Acknowledgements
The authors would like to acknowledge partial support for
fulfillment of this work by grant NSC 92-2214-E-011-017 issued
from the National Science Council of Taiwan.