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The Mystery of the Source of Life: What is the Pre-Replication Complex (pre-RC)?
In the mysterious and delicate cell cycle, the pre-replication complex (pre-RC) plays a crucial role, especially in initiating DNA replication. It is an important link in the cell replication process. Without it, complete replication of DNA will not be achieved, allowing each daughter cell to carry the same genetic information as the parent cell. This article will explore in depth the composition, role and changes of pre-RC in different life forms.
Composition of the prereplication complex
With the process of biological evolution, the composition of the pre-RC has become more complex. The composition of the anterior RC is significantly different in different life domains.
In bacteria, the main component of the pre-RC is DnaA. The pre-RC is formed when DnaA occupies all binding sites in oriC, the origin of bacterial replication.
For Archaea, the composition of the pre-RC is very different, containing a single origin recognition complex (ORC) protein, Cdc6/ORC1, and a hexameric minichromosome maintenance (MCM) protein. The pre-RC of eukaryotes is the most complex and usually consists of six ORC proteins (ORC1-6), Cdc6, Cdt1 and six MCM proteins (MCM2-7).
Identify the origin of replication
Identification of the origin of replication is the first step in the formation of pre-RC, which is accomplished in different ways in different domains of life. For prokaryotes, this step is mediated by DnaA. DnaA binds tightly to the 9 base pair consensus sequence in oriC.
In Archaea, origin identification usually relies on an AT-rich sequence. In eukaryotes, there are multiple origins of replication.
Loading process
The assembly of the prereplication complex only occurs in the late M phase and early G1 phase of the cell cycle, when cycle-dependent kinase (CDK) activity is low to ensure that DNA replication can only occur once per cell cycle. .
Copy start
After the formation of the pre-RC, activation and assembly of the replisome must occur before DNA replication can begin. In prokaryotes, DnaA hydrolyzes ATP to unravel the DNA at oriC, providing the space needed for replication and starting the replication process.
In eukaryotes, phosphorylation of the MCM hexamer is carried out by CDC7 and CDK, which allows the exclusion of Cdc6 and the recruitment of MCM10.
Prevention of reassembly of proreplication complexes
During each cell cycle, it is important that the genome is completely replicated once and only once. Therefore, the composition of the pre-RC must be tightly controlled to ensure that it does not form again after DNA replication is completed.
Meier-Gorlin Syndrome
In eukaryotes, defects in components of the prereplication complex are associated with Meier-Gorlin syndrome, a disorder characterized by dwarfism, missing or underdeveloped hip joints, small ears, and poor neonatal and postnatal growth. Diseases with other characteristics.
In summary, the prereplicative complex plays a key role in the life process of organisms. Without it, organisms cannot ensure the accurate transmission of genetic information in each cell division. Have you ever thought about what unknown mysteries there are in the reproduction process of life that need to be explored?
