S.E.colization :
Green light, Go !
Aix-Marseille University 2014 Team
Advisors : Aurélie Dobric
Collaborators : Dr. E. Bouveret (LISM, Marseille)
Ressources : Dr. J. Dueber (Berkeley University, USA) and Dr. B.
Aimeric
AGAOUA
Lambert
ANTONI
Clara
BOUYX
Alexia
SATOUF
Romain
VEILLARD
Vincent
CASTEL
Students
James
STURGIS
Gaël
CHAMBONNIER
Laetitia
HOUOT
Sandra
MICHEL-SOUZY
Field (Laboratoire de Génétique et Biophysique des Plantes, Marseille)
Supervisors
Serine receptors (Tsr) desactivated
Autophosphorylation of CheA
Increased level of serine
Overexpression of RelA
Serine production stopped
Division of bacteria
Autophosphorylation of CheA inhibited
Overexpression of Mesh1
Controlling cell Division :
Rewiring Intracellular signaling :
We control cell division using [ppGpp] modulated
by RelA and Mesh1. To validate our part
BBa_K1349001 (RelA coding sequence), we used
a mutant unable to synthetize RelA, and growing
very slowly. When we complement this strain with
BBa_K1349001, bacteria normal growth is
restored. Our RelA part is functionnal.
To modulate expression of genes, we used phosphorylation
of the regulator CusR. CusR binds to CusR box sequences
in reponse to metallic stress (Cu, Ag). To validate our part
BBA_K1349002 (CusR box sequence), we grew cells in the
presence of Ag. As expected, 2 or 3 CusR boxes on a
plasmid sequester the endogenous CusR, preventing the
normal detoxication of the cells.
Figure 1 : The presence of RelA
gene restore a normal growth in
MG1655∆relA strain
Figure 2 : The presence of cusR boxes on a
pLac vector affects cell growth in the
presence of a sub-lethal dose of AgNO3.
Modeling :
Beyond the bench :
« Synthetic » + « Biology »…how does it sound for the public?
The Messenger has to be a
trusted source (ie a scientist!)
You want a balanced and credible message.
Avoid sensational!!!
Our goal : identify some key rules to communicate
efficiently on Synthetic Biology (SB) to a broad audience.
Our resources: bibliography + our own experiences “on
field” (presentation to local media, sponsors, and during
Be prepared to have tricky questions about safety, ethic
the French Science Festival “Fête de la Science”)
and responsibilities for this emerging technology.
A computer simulation of the designed system shows
that CusR, and ppGpp can oscillate as the system grows
and serine accumulates. We implemented our
simulation in Matlab, using a set of differential
equations that we integrated numerically using
a Runge-Kutta 4 algorithm.
Figure 3 : Modeling of our biological model