The yeast proteases Ddi1 and Wss1 are both involved in the DNA replication stress response

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Genome integrity and cell survival rely on effective replication stress response pathways.
• Understanding these pathways is vital for treating human diseases linked to DNA damage.
• Two proteases, yeast Wss1 and Ddi1, are implicated in DNA replication stress response.

Purpose of the Study:

• To investigate the genetic interaction between yeast Wss1 and Ddi1 proteases.
• To elucidate the functional roles of these proteases in response to replication stress.
• To explore the involvement of Ddi1's helical domain in DNA replication stress.

Main Methods:

• Genetic analysis of double deletion mutants (Δddi1, Δwss1) in yeast.
• Phenotypic analysis of sensitivity to hydroxyurea, a replication-blocking drug.
• Complementation studies using catalytically competent Ddi1 protease.
• Functional characterization of Ddi1 domains in replication stress response.

Main Results:

• The Δddi1, Δwss1 yeast strain exhibits hypersensitivity to hydroxyurea.
• This hypersensitivity is rescued specifically by catalytically active Ddi1 protease.
• The helical domain of Ddi1 plays a critical role in responding to hydroxyurea-induced replication stress.

Conclusions:

• A strong negative genetic interaction exists between Wss1 and Ddi1 proteases in yeast.
• A novel dual protease mechanism involving Wss1 and Ddi1 contributes to counteracting DNA replication stress.
• The N-terminal helical domain of Ddi1 has a previously unrecognized function in replication stress response.