A bacterial type II enzyme, called either topoisomerase II or DNA gyrase, can introduce negative supercoils (decrease Lk). It uses the energy of ATP to accomplish this.

To alter DNA linking number, type II topoisomerases cleave both strands of a DNA molecule and pass another duplex through the break.

TLS Online TPP Program

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#Unit 3. Fundamental Processes

Each eukaryotic chromosome contains a large number of replicons spaced unevenly throughout the chromosomes.

TLS Online TPP Program

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#Unit 3. Fundamental Processes

The bacterial DnaA protein is the replication initiator; it binds sequence specifically to multiple sites (dnaA boxes) in oriC.

TLS Online TPP Program

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#Unit 3. Fundamental Processes

Activity of the replication origin is controlled is DNA methylation

TLS Online TPP Program

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#Unit 3. Fundamental Processes

The E. coli oriC contains 11 copies of the GATC sequence

TLS Online TPP Program

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#Unit 3. Fundamental Processes

GATC is a target for methylation at the N6 position of A by Dam Methylase enzyme which uses SAM as methyl group donor

TLS Online TPP Program

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#Unit 3. Fundamental Processes

Several of methylation sites overlap dnaA boxes