Team:Newcastle/the problem


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Linear DNA clock: Richard

Initial idea 12 February 2010

Builds on idea about protecting against mutations. Rather than wait for a mutation to 
happen, could guarantee that genetically-engineered BS cell will not survive after a certain 
time. Idea is to linearise prokaryotic dna and insert two genes: one a repressor protein at 
a variable short distance from the cleaved site, and 2) a gene that codes for a cell-
destroying protein of some sort which the repressor protein usually inhibits. 
Remember telomeres? Idea is that every time the BS divides, its dna will become progressively 
shorter from either end. Thus the gene for the repressor protein will get eaten away. After 
time x (can be set by experimenter) the repressor gene will be rendered non-functional and 
no repressor protein is produced. This means that the second gene we inserted, which codes 
for the cell-destroying protein is free to kill the cell. No mutation, no residual problem 
of removing BS after treatment by idea 3.
At some point in evolution in the move from prokaryotic to eukaryotic genomes, the dna became 
linearised, so shouldn’t be such a hard problem to solve if we want the dna to stay this way. 
Could insert a piece of linear dna containing linear transcription machinery on it as well.

Ongoing references

Baker et al. 2007 A Novel Linear Plasmid Mediates Flagellar Variation in Salmonella Typhi.Took linear plasmid from S.Typhi and transformed into E.coli [1].

Baker et al. 2007 A linear plasmid truncation induces unidirectional flagellar phase change in H:z66 positive Salmonella Typhi. More info on this linear plasmid [2].

Cui et al 2007 Escherichia coli with a linear genome. Linearises genome of E.coli [3].


Literature research and plan [4]

Presentation delivered at informal meeting on 26 Feb [5]