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Structure-based interpretation of missense mutations in Y-family DNA polymerases and their implications for
François Boudsocq1, Hong Ling, Wei Yang
1Section on DNA Replication, Repair and Mutagenesis, Building 6, Room 1A13, National Institute of Child Health and Human Development, National Institutes of Health, 9000 Rockville Pike, Bethesda MD 20892-2725, USA.
Abstract:
Our understanding of the molecular mechanisms of error-prone lesion bypass has changed dramatically in the past few years. The concept that the key participants in the mutagenic process were accessory proteins that somehow modified the ability of the cell's main replicase to facilitate bypass of normally blocking lesions has been replaced with one in which the replicase is displaced by a polymerase specialized in lesion bypass. The participants in this process remain the same, only their function has been reassigned. What was once known as the UmuC/DinB/Rev1/Rad30 superfamily of mutagenesis proteins, is now known as the Y-family of DNA polymerases. Quite remarkably, within the space of 3 years, the field has advanced from the initial discovery of intrinsic polymerase function, to the determination of the tertiary structures of several Y-family DNA polymerases.A key to determining the biochemical properties of each DNA polymerase is through structure-function studies that result in the site-specific substitution of particular amino acids at critical sites within each DNA polymerase. However, we should not forget the power of genetic selection that allows us to identify residues within each polymerase that are generated by "random mutagenesis" and which are important for both a gain or loss of function in vivo. In this review, we discuss the structural ramifications of several missense mutations previously identified in various Y-family DNA polymerase and speculate on how each amino acid substitution might modify the enzymatic activity of the respective polymerase or possibly perturb protein-protein interactions necessary for efficient translesion replication in vivo.
Insights
The Y-family of DNA polymerases, formerly mutagenesis proteins, are now understood to displace replicases for error-prone lesion bypass. Structure-function studies reveal how mutations in these polymerases impact DNA repair and replication.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Understanding of error-prone DNA lesion bypass has shifted from accessory proteins to specialized Y-family DNA polymerases.
- The Y-family of DNA polymerases (previously UmuC/DinB/Rev1/Rad30) are key players in mutagenic bypass.
- Significant advancements include the discovery of intrinsic polymerase function and determination of Y-family DNA polymerase structures.
Purpose of the Study:
- To review the structural effects of missense mutations in Y-family DNA polymerases.
- To explore how amino acid substitutions alter enzymatic activity and protein interactions.
- To connect in vitro structure-function data with in vivo genetic selection findings.
Main Methods:
- Analysis of existing literature on Y-family DNA polymerases.
- Structure-function studies involving site-specific amino acid substitutions.
- Review of genetic selection data identifying key residues through random mutagenesis.
Main Results:
- Missense mutations can alter the enzymatic activity of Y-family DNA polymerases.
- Amino acid substitutions may affect crucial protein-protein interactions in translesion replication.
- Both structural and genetic approaches are vital for understanding polymerase function.
Conclusions:
- The functional reassignment of Y-family polymerases highlights a paradigm shift in DNA repair research.
- Structure-function studies and genetic analysis provide complementary insights into polymerase mechanisms.
- Further research into Y-family DNA polymerases is crucial for understanding genome stability and mutagenesis.