$~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
\newcommand{\MyColi}{{\small Mighty\hspace{0.12cm}Coli}}
\newcommand{\Stabi}{\small Stabi}$
$\newcommand{\EColi}{\small E.coli}
\newcommand{\SCere}{\small S.cerevisae}\\[0cm]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
\newcommand{\PI}{\small PI}$
$\newcommand{\Igo}{\Large\mathcal{I}}
\newcommand{\Tgo}{\Large\mathcal{T}}
\newcommand{\Ogo}{\Large\mathcal{O}}
~$
Example of a hierarchical menu in CSS
Now we're ready to compare our $\MyColi$ with the usual $\Stabi$ system.
The objective of $\Stabi$ is to stabilize the presence of the plasmids that contain the $\PI$ gene sequence.
$\EColi$ can insert other plasmids, containing the $\Tox$ and the $\AnTox$ genes.
These two proteins are produced at same rate (contitutive promoter: T7) and the $\PI$ is independently produced in this classical system.
The objective of $\MyColi$ is a little bit different: The T7 promoter iniciates the transcription of the $\PI$ $\small\&$ the $\AnTox$ genes, but another promoter, pBAD, controls the transcription of the $\Tox$ gene, situated in another plasmid than the $\PI$ $\small\&$ the $\AnTox$ genes.
The problem with the classical system is that if there are a lot of mutations or a lot of heterogeneity in the $\EColi$ population, the $\PI$ is not produced at high rate. In a bioreactor built to product a special kind of $\PI$, this system's not optimal because there're $\PI$ losses, especially if the $\PI$ gene sequence is long or if the $\PI$ is cumbersome for $\EColi$.
With our $\MyColi$ system, the sub-producing bacteria are eliminated from the bioreactor because these $\EColi$ don't produce the $\PI$ in sufficient quantity (the $\PI$ is produced at same rate than the $\AnTox$, thanks to the $2A$ $peptid$). Because the presence of the $p2A$ is necessary with $\MyColi$, the losses can be divided in two classes:
(1) bacteria without cleavage of p2A $\hspace{0.1cm}\small\&\hspace{0.1cm}$ (2) bacteria killed by TA system, when there's more $\Tox$ than $\AnTox$ (this's when the fraction [$\Tox$]/[$\AnTox$] is bigger than one, this happens when a lot of $AnTox$ are degraded and when $Tox$ is produced at high rate).
To only take a sight in the $\MyColi$ mechanism, we'll assume that $\EColi$ is virtually immortal (no relation between the producing rate of proteins and the old age of some members of the population) and that $\Tox$ and $\AnTox$ recombine rapidly in TA-complex (no dependence with the mean free path of proteins into the cytoplasm).
-Du nouveau pour comparer avec et sans p2A? Yes, now we get it!
"
- Université Libre de Bruxelles -
