Biology Reference
In-Depth Information
291
FIGURE 15.5A
Theoretical protein-based minimal cell: in the illustration the minimal genome is incorporated into a lipid bilayer along with a
purified transcription/translation system. For the creation of a self-replicating/self-sustaining minimal cell, the cell must be
able to efficiently transcribe RNA and translate the genome into proteins that are then able to sustain the cell and additionally
aid in replication of all the components of the cell.
gradually decreases; and (2) the PCR conditions that are used to replicate the DNA in the
giant vesicle would cause denaturation of any proteins that were synthesized or introduced
into the vesicle to create a fully competent minimal cell. In a third example, controlled
vesicle fusion of oppositely charged vesicles demonstrated for the first time the ability to
'
and maintain metabolism in minimal cell models. Specifically, vesicles containing
either DNA or RNA polymerase could trigger gene expression when fused. This method
provides a means to introduce larger biomolecules into the system that are unable to diffuse
through the pore.
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regulate
'
Outside of efforts to create membranes that can grow, divide, and integrate cellular
processes, another key area of growth has centered on relieving limitations imposed on
nutritional and energy requirements in a minimal cell. One landmark study was the
creation of pores (the
-hemolysin protein from
Streptomyces aureus
) in a phospolipid
membrane that encapsulated a cell-free protein synthesis reaction (
Fig. 15.5C
).
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This pore
enabled selective permeabilization to realize long-lived cell-free transcription and
translation.
α
In addition to developments in membranous minimal cellular compartments, activating
complex biochemical processes inside vesicles is required for self-replication. Recent
