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Published on: February 13, 2019
Yeast RAD14 and human xeroderma pigmentosum group A DNA-repair genes encode homologous proteins
M Bankmann1, L Prakash, S Prakash
1Department of Biophysics, University of Rochester School of Medicine, New York 14642-8408.
Abstract:
Xeroderma pigmentosum (XP), a human autosomal recessive disorder, is characterized by extreme sensitivity to sunlight and high incidence of skin cancers. XP cells are defective in the incision step of excision repair of DNA damaged by ultraviolet light. Cell fusion studies have defined seven XP complementation groups, XP-A to XP-G. Similar genetic complexity of excision repair is observed in the yeast Saccharomyces cerevisiae. Mutations in any one of five yeast genes, RAD1, RAD2, RAD3, RAD4, and RAD10, cause a total defect in incision and an extreme sensitivity to ultraviolet light. Here we report the characterization of the yeast RAD14 gene. The available rad14 point mutant is only moderately ultraviolet-sensitive, and it performs a substantial amount of incision of damaged DNA. Our studies with the rad14 deletion (delta) mutation indicate an absolute requirement of RAD14 in incision. RAD14 encodes a highly hydrophilic protein of 247 amino acids containing zinc-finger motifs, and it is similar to the protein encoded by the human XPAC gene that complements XP group A cell lines.
Insights
Xeroderma pigmentosum (XP) involves DNA repair defects. The yeast RAD14 gene is crucial for DNA incision, a key step in repairing UV damage, similar to human XP genes.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Xeroderma pigmentosum (XP) is an autosomal recessive disorder in humans.
- XP is characterized by extreme sun sensitivity and high skin cancer incidence.
- XP cells exhibit defects in the incision step of DNA excision repair following UV damage.
Purpose of the Study:
- To characterize the function of the yeast RAD14 gene in DNA repair.
- To investigate the role of RAD14 in the incision step of nucleotide excision repair.
- To compare RAD14 with human XP genes.
Main Methods:
- Genetic analysis of yeast mutants (point and deletion).
- DNA incision assays to assess repair capacity.
- Protein analysis of RAD14, including sequence and motif identification.
Main Results:
- A rad14 point mutant showed moderate UV sensitivity and substantial DNA incision.
- A rad14 deletion mutant demonstrated an absolute requirement for RAD14 in DNA incision.
- RAD14 encodes a 247-amino acid protein with zinc-finger motifs, similar to human XPAC.
Conclusions:
- RAD14 is essential for the incision step in yeast DNA repair.
- The findings highlight the conserved genetic complexity of DNA repair in yeast and humans.
- RAD14 represents a potential functional homolog of the human XPAC gene.
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