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Mec1/Tel1 phosphorylation of the INO80 chromatin remodeling complex influences DNA damage checkpoint responses
Ashby J Morrison1, Jung-Ae Kim, Maria D Person
1Department of Carcinogenesis, Science Park Research Division, University of Texas M.D. Anderson Cancer Center, Smithville, TX 78957, USA.
Abstract:
The yeast Mec1/Tel1 kinases, ATM/ATR in mammals, coordinate the DNA damage response by phosphorylating proteins involved in DNA repair and checkpoint pathways. Recently, ATP-dependent chromatin remodeling complexes, such as the INO80 complex, have also been implicated in DNA damage responses, although regulatory mechanisms that direct their function remain unknown. Here, we show that the Ies4 subunit of the INO80 complex is phosphorylated by the Mec1/Tel1 kinases during exposure to DNA-damaging agents. Mutation of Ies4's phosphorylation sites does not significantly affect DNA repair processes, but does influence DNA damage checkpoint responses. Additionally, ies4 phosphorylation mutants are linked to the function of checkpoint regulators, such as the replication checkpoint factors Tof1 and Rad53. These findings establish a chromatin remodeling complex as a functional component in the Mec1/Tel1 DNA damage signaling pathway that modulates checkpoint responses and suggest that posttranslational modification of chromatin remodeling complexes regulates their involvement in distinct processes.
Insights
Yeast Mec1/Tel1 kinases phosphorylate the INO80 chromatin remodeling complex during DNA damage. This posttranslational modification impacts DNA damage checkpoint responses, not DNA repair itself.
Area of Science:
- Molecular Biology
- Cellular Biology
- Biochemistry
Background:
- DNA damage response pathways are crucial for maintaining genomic stability.
- Mec1/Tel1 kinases (ATM/ATR in mammals) are key regulators of DNA damage response.
- ATP-dependent chromatin remodeling complexes, like INO80, are involved in DNA damage response, but their regulation is unclear.
Purpose of the Study:
- To investigate the regulatory mechanisms of the INO80 chromatin remodeling complex in DNA damage response.
- To determine if Mec1/Tel1 kinases directly regulate the INO80 complex.
- To elucidate the role of Ies4 subunit phosphorylation in DNA damage signaling.
Main Methods:
- Yeast genetics and molecular biology techniques.
- Phosphorylation site mutagenesis of the Ies4 subunit.
- Analysis of DNA repair and DNA damage checkpoint phenotypes.
- Western blotting to detect protein phosphorylation.
Main Results:
- The Ies4 subunit of the INO80 complex is phosphorylated by Mec1/Tel1 kinases upon DNA damage.
- Mutations in Ies4 phosphorylation sites did not impair DNA repair but affected DNA damage checkpoint responses.
- Ies4 phosphorylation is linked to the function of checkpoint regulators like Tof1 and Rad53.
Conclusions:
- The INO80 chromatin remodeling complex is a functional component of the Mec1/Tel1 DNA damage signaling pathway.
- Posttranslational modification, specifically phosphorylation of Ies4, modulates the function of chromatin remodelers in DNA damage checkpoints.
- This study reveals a novel regulatory mechanism for chromatin remodeling complexes in response to DNA damage.
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