Mutant PCNA Enhances DNA Replication Versatility
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Solution Overview
Problem
Current PCR technologies face limitations in achieving balanced extendibility and fidelity in DNA amplification, with existing DNA polymerases and PCNA-RFC systems either excelling in one aspect at the expense of the other, and requiring RFC for optimal performance.
Innovation Solution
A novel DNA amplification system is developed using a mutant PCNA that forms a multimeric complex with intermolecular interactions in its interface region, promoting DNA extension reactions without the need for RFC, enhancing both extendibility and fidelity across various DNA polymerases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RFC is used with wild-type PCNA to achieve optimal DNA replication, then fidelity is improved, but device complexity increases and versatility decreases
Solution Approach 1:
The invention extracts and modifies the PCNA protein to create a mutant form that inherently possesses enhanced DNA replication function without requiring RFC. By removing the dependency on RFC from the system, the complexity is reduced while maintaining high fidelity through the mutated PCNA's intrinsic properties
Solution Approach 2:
The mutant PCNA is designed to perform multiple functions independently - it can function with various DNA polymerases (both α-type and Pol I-type) without requiring RFC, making it a universal component that simplifies the overall system while maintaining high reliability across different polymerase types
2Reliability
If α-type DNA polymerase with proof reading function is used to enhance fidelity, then reliability is improved, but extendibility deteriorates
Solution Approach 1:
The mutant PCNA acts as an intermediary that bridges the gap between fidelity and extendibility. It binds to and stimulates both α-type DNA polymerase (high fidelity) and Pol I-type DNA polymerase (high extendibility), allowing the system to achieve both properties simultaneously without requiring a single polymerase to possess both traits
3Length of moving object
If Pol I-type DNA polymerase is used to enhance extendibility, then length of amplifiable sequence is improved, but fidelity deteriorates
Solution Approach 1:
The mutant PCNA serves as a mediator that enables both high-fidelity α-type polymerase and high-extendibility Pol I-type polymerase to function effectively. By stimulating both polymerase types, it allows the system to achieve both extendibility and fidelity, with the specific polymerase choice depending on the particular application requirements
4Productivity
If mutant PCNA is used to achieve high versatility and reaction rate without RFC, then productivity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The invention applies parameter changes at the protein sequence level by introducing specific amino acid mutations at defined positions (e.g., positions 143 and 147) in the PCNA protein. These precise parameter changes in the protein structure enable the mutant PCNA to achieve enhanced functionality and versatility while maintaining controllable manufacturing precision through well-defined mutation sites
Data Source
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AI summary
The present invention is to construct a DNA replication reaction system which is excellent in versatility and is easily used. An amino acid sequence of a PCNA monomer which is one of factors involved in DNA replication is prepared so that amino acid residues causing mutual charge repulsion constitute a site which causes, when an N terminal region of the PCNA monomer and a C. terminal region of another PCNA monomer act as an interface to form a multimeric complex, an intermolecular interaction of the monomers in an interface region of the monomers.