From bacteria to artificial cells.
The problem of self reproduction
Albert Libchaber
Rockefeller University
Institute for Advanced Study
Model organism
Bacteria: Escherichia coli (E. coli)
Well studied bacteria
at normal conditions.
Average size = 2mm
Division time = 30 min,
P=1atm, T=37oC
~1014 in 24 hours
Bacteria under pressure
Pressure dependence of doubling time
II
I
Growth rate decreases upon increasing pressure with a
sharp decrease at high pressure.
Recovery of MreB upon
depressurization
t=0min
t=500min
t=270min
t=590min
t=390min
t=1000min
Kumar, Libchaber (preprint)
In his theory of automata John Von Neumann
compared computing machines and living
organisms.
The self reproduction of automata (1948), was
discussed and linked to a Turing like principle.
Von Neumann logic implied that self
reproduction needed a memory and a code. This
was proposed before Crick and Watson model of
DNA.
J. Von Neumann Hixon Symposium 1951
Can we synthesize the most elementary cell size
compartment that can self reproduce using genetic
information only?
This would follow Von Neumann logic for self- reproduction
.
J.Von Neumann Theory of self –reproducing automata (1966)
It is easy to encapsulate a cellular extract plus
a DNA program into a phospholipid vesicle
Noireaux & Libchaber PNAS 101, 17669 (2004)
Noireaux University of Minnesota
Cell-free Transcription-Translation system
A cellular extract
• 1961:First cell-free protein synthesis study.
The genetic code (Matthaei and Nirenberg)
• 70s: Gene regulation unraveled with cell-free systems.
• 90s: Invention of the efficient hybrid cell-free system (Spirin).
- large scale protein synthesis.
- high throughput proteomics.
- protein evolution.
- industrial applications.
12
Vincent Noireaux lab
Phage T7
●
●
●
●
●
lytic coliphage.
40 kbp, 60 genes (35 with known functions).
almost host independent (2 host proteins required).
has its own RNA polymerase.
has its own DNA polymerase.
13
Vincent Noireaux lab
Phage T7 synthesis in a test tube
Transcription
genome
Translation
mRNA
phage
Replication ONLY
● TEM image
● 5-6 hours of incubation
● batch mode reaction
J.Shin & V.Noireaux ACS synthetic biology 1, 408 (2012)
14
A
B
geodesics
YFP-MreB
Rhodamine-BSA
C
Y.T.Maeda, et al. ACS synthetic biology 1 (2011)
Merged
Microbes in the soil ecosystem
Alex Petroff , A.L
Rockefeller University
Conclusion
Physics to Biology :
Duality: Sequence space versus object space
Genetic code, Self Reference, Self Reproduction.
Dangerous dynamics leading to a world of exponentials.
Metabolism needs to follow. Darwinian evolution possible.
The environment is a fundamental aspect of cellular life.
It controls metabolism, development and organization.
Research on artificial life is very active in laboratories.