DNA damage induction of ribonucleotide reductase

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Ribonucleotide reductase (RNR) is essential for DNA synthesis.
• RNR2, the gene encoding its small subunit, is cell cycle regulated and induced by DNA damage.
• Understanding RNR2 regulation is key to DNA repair mechanisms.

Purpose of the Study:

• To investigate the regulation of the RNR2 gene.
• To characterize the DNA damage response pathway involving RNR2.
• To analyze the effects of specific mutations on RNR2 induction.

Main Methods:

• Utilized an RNR2-lacZ fusion in yeast to measure RNR2 gene expression.
• Exposed yeast strains to various DNA-damaging agents (UV, 4-NQO, MMS) and replication inhibitors (HU, methotrexate).
• Assessed RNR2 induction in different cell cycle phases and in the presence of cycloheximide.
• Analyzed RNR2 induction in rnr2-314 and rad4-2 mutant strains.

Main Results:

• RNR2 expression was induced by DNA damage and replication stress, but not heat shock.
• RNR2 induction occurred outside of S phase and was independent of de novo protein synthesis.
• The rnr2-314 mutation led to constitutive DNA damage response and hypersensitivity to HU.
• RNR2 induction showed differential sensitivity to DNA-damaging agents in rad4-2 mutants.
• The DNA damage stress response was confirmed to be cell-autonomous.

Conclusions:

• RNR2 regulation is tightly controlled in response to DNA damage and replication stress.
• The RNR2 pathway's response is complex and involves multiple genetic factors.
• The rnr2-314 mutation provides insights into constitutive DNA repair mechanisms.
• The study highlights the cell-autonomous nature of the DNA damage response.