Termination of dna synthesis in e. coli and humans differ significantly because of the genomic structures involved, namely a circular genome in bacteria and linear chromosomes in humans. briefly describe structure and function of the one key e. coli protein and the one key human protein that are each needed for high fidelity termination of dna replication.
Question: Termination of dna synthesis in e. coli and humans differ significantly because of the genomic structures involved, namely a circular genome in bacteria and linear chromosomes in humans. briefly describe structure and function of the one key e. coli protein and the one key human protein that are each needed for high fidelity termination of dna replication.
In E. coli, the key protein involved in high fidelity termination of DNA replication is called Tus (Termination utilization substance). Tus is a DNA-binding protein that plays a critical role in preventing replication forks from colliding with each other during the termination process. It binds to specific sequences called Ter sites (Termination sites) present in the E. coli genome.
When the replication machinery encounters a Ter site, the Tus protein binds to it, creating a Tus-Ter complex. This complex acts as a barrier for other replication forks attempting to pass through the same region. As a result, the replication fork coming from one direction is stalled while the replication fork from the opposite direction continues. This ensures that the two forks are separated and replication terminates in a controlled and high-fidelity manner.
In humans and other eukaryotes with linear chromosomes, the key protein involved in high fidelity termination of DNA replication is called Termination of Replication 1 (Ter1) or ORC1 (Origin Recognition Complex 1). ORC1 is a subunit of the Origin Recognition Complex (ORC), which is essential for the initiation of DNA replication at origins of replication.
During termination, ORC1 acts as a key factor in coordinating the termination process. It helps in the proper disassembly and inactivation of the replication machinery at the replication forks' end. By ensuring that the replication process is correctly halted and the replication machinery is disengaged, ORC1 contributes to the high fidelity and accurate termination of DNA replication in linear chromosomes.
It's important to note that while the proteins involved in termination are different in E. coli and humans, their fundamental roles are similar - to prevent conflicts between replication forks and ensure accurate and reliable termination of DNA synthesis. The differences in genomic structures, circular genome in bacteria and linear chromosomes in humans, necessitate distinct molecular mechanisms for DNA replication termination in each organism.
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