PCR
test
Agarose Gel Electrophoresis
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Team:SIAT-SCIE/Design
Chassis
In our project, we used E.coli BW25113 strain with OmpA gene knocked out for the reason that the absence of OmpA protein would lead to hyper-vesiculation, meaning increased production of outer membrane vesicles (OMVs).
Inside the periplasm there is a thin, rigid peptidoglycan(PG) layer attached to both outer membrane and cytoplasmic membrane by membrane anchored proteins.[Fig. 1](1) Deletion or truncation of OmpA, an abundant protein linking the outer membrane and peptidoglycan layer, will therefore result in increased vesiculation in E. coli, Salmonella, and Vibrio cholerae (2) as the Figure 1 lack of OmpA destabilises the periplasm’s structure.This will result in greater likelihood that our Cas9 protein will be encapsulated into OMVs.
Importing Proteins into Periplasm Through TAT Pathway
To allow proteins to be encapsulated in OMVs, they need to be imported into bacteria’s periplasm first. Compared to other common transporting pathways that transport proteins before folding (e.g. Sec and SRP-dependent pathways), twin arginine transport (TAT) pathway is an available option for transportation of fully folded proteins(3). This is crucial since some proteins, including GFP, cannot fold properly when transported into periplasm(3).
Thus, they have to complete their folding in cytoplasm before they can be transported to periplasm. Consequently, TAT pathway is the only plausible option[Fig. 2]. Regarding the Cas9 proteins, since there has been no literature discussing the possibility of their possible Figure 2 of folding in periplasm, we chose TAT pathway for Cas9 proteins as well out of prudence.