A strain of E. coli has a mutation in the dnaA gene resulting in a DnaA protein

Question

A strain of E. coli has a mutation in the dnaA gene resulting in a DnaA protein that binds DNA non-specifically (i.e., not just at the origin). How would the process of replication be affected in this cell? Assume that the amount of DnaA is not limiting. You construct an engineered E. coli strain that produces high levels of a modified Dam (DNA-adenine methylase) that functions faster and more efficiently than the normal E. coli Dam. How would the rate of replication be affected in this strain? Why would it have this effect?

Explanation / Answer

2. Mutation in the dnaA Gene results in the formation of a defective dnaA protein. Due to mutation it binds non-specifically to the template DNA strand that should undergo replication.

This DnaA protein binds at the origin to start the replication of the DNA strand. However due to non-specific binding, the mutated dnaA protein binds anywhere to the DNA template strand and begins replication. This anamoly results in incorrect and incomplete replication of the DNA and finally results in defective and incomplete mRNA strand.

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