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Ixr1, a yeast protein that binds to platinated DNA and confers sensitivity to cisplatin
S J Brown1, P J Kellett, S J Lippard
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139.
Abstract:
Structure-specific recognition proteins (SSRPs) bind to DNA containing intrastrand cross-links formed by the anticancer drug cisplatin. A yeast gene encoding an SSRP, designated IXR1, was cloned and sequenced. The Ixr1 protein, a member of the high mobility group-box protein family, bound specifically to DNA modified with cisplatin but not inactive platinum compounds. A yeast strain with an inactivated IXR1 gene was half as sensitive to cisplatin and accumulated one-third as many platinum-DNA lesions after treatment with cisplatin as the parental strain. These findings suggest that SSRPs play a role in mediating the cytotoxicity of cisplatin.
Insights
Structure-specific recognition proteins (SSRPs) bind to DNA damaged by cisplatin. Researchers identified a yeast SSRP, Ixr1, crucial for recognizing these platinum-DNA adducts and mediating cisplatin
Area of Science:
- Molecular biology
- Cancer research
- DNA repair mechanisms
Background:
- Anticancer drugs like cisplatin induce DNA damage.
- Structure-specific recognition proteins (SSRPs) are involved in DNA binding.
- The role of SSRPs in cisplatin cytotoxicity is not fully understood.
Purpose of the Study:
- To identify and characterize SSRPs involved in recognizing cisplatin-induced DNA damage.
- To investigate the function of a specific SSRP, Ixr1, in yeast.
- To determine the contribution of Ixr1 to cellular sensitivity to cisplatin.
Main Methods:
- Cloning and sequencing of the yeast IXR1 gene.
- Biochemical assays to assess Ixr1 binding to cisplatin-modified DNA.
- Construction and characterization of a yeast strain with inactivated IXR1.
- Measurement of cisplatin sensitivity and platinum-DNA adduct accumulation in yeast strains.
Main Results:
- The yeast IXR1 gene encodes a high mobility group-box protein.
- Ixr1 protein specifically binds to DNA containing cisplatin-induced intrastrand cross-links.
- Yeast strains lacking functional IXR1 exhibit reduced sensitivity to cisplatin.
- Inactivated IXR1 strains accumulate fewer platinum-DNA lesions after cisplatin treatment.
Conclusions:
- SSRPs, exemplified by Ixr1, play a significant role in recognizing DNA damage caused by cisplatin.
- Ixr1 contributes to mediating the cytotoxic effects of cisplatin in yeast.
- These findings highlight the importance of SSRPs in DNA damage response pathways relevant to cancer therapy.