Question

Describe the role that integrase plays during the insertion of \(\lambda\) DNA into the host chromosome.

Short answer

Integrase is a site-specific recombinase enzyme that plays a crucial role during the insertion of lambda DNA into the host chromosome by recognizing attachment sites on the phage and host DNA and catalyzing their recombination. This results in the integration of the phage DNA into the host chromosome, allowing the cell to transcribe and translate the phage DNA along with its own.

Step-by-step solution

Description of the Lambda Phage Replication

Lambda phage is a type of bacteriophage that infects bacteria, in particular E. coli. After infection, it can engage in a lysogenic or lytic cycle. In the lysogenic cycle, the phage's DNA is integrated into the bacterial cell's chromosome, becoming a prophage. This exercise focuses on the lysogenic cycle.

Role of Integrase in the Lysogenic Cycle

The integration of lambda phage DNA into the host bacterial chromosome is facilitated by the enzyme Integrase. Integrase is a site-specific recombinase, which means that it recombines DNA at specific sites. This enzyme recognizes attachment sites on the phage DNA (attP) and the bacterial DNA (attB), and catalyzes the recombination of these sequences.

DNA Integration Process

Integrase binds to both the phage and host DNA, lining them up so that specific bases on one DNA strand pair with specific bases on the other. The breaking and rejoining of the DNA strands, which results in the integration of the phage DNA into the host chromosome, is then catalyzed by Integrase. The end result is that the lambda phage DNA is now a part of the host bacterial chromosome, and the cell will transcribe and translate the phage DNA along with its own.