Giant yeast cells with nonrecyclable ribonucleotide reductase

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Ribonucleotide reductase (RNR) is essential for DNA synthesis and repair by converting ribonucleotides to deoxyribonucleotides.
• Understanding cellular responses to replicational stress is crucial for comprehending DNA maintenance mechanisms.

Purpose of the Study:

• To investigate the adaptability of Saccharomyces cerevisiae to permanent replicational stress.
• To create a yeast model system for studying cellular resilience under continuous DNA synthesis demands.

Main Methods:

• Construction of a Saccharomyces cerevisiae mutant (rnr1C883A rnr3Δ) with non-recyclable RNR catalytic subunits.
• Analysis of cell cycle progression, protein production, and checkpoint activation (Rad53) under induced stress.
• Phenotypic characterization including cell volume and inclusion body formation.

Main Results:

• The rnr1C883A rnr3Δ mutant experiences constitutive replicational stress with an extended S phase.
• Cells exhibit significant morphological changes, including an 8-fold increase in cell volume and inclusion bodies.
• Despite stress, the mutant maintains good plating efficiency and indefinite propagation, indicating cellular robustness.

Conclusions:

• Saccharomyces cerevisiae exhibits remarkable robustness in tolerating sustained replicational stress and associated physiological perturbations.
• The engineered mutant serves as a valuable system for protein overexpression and studying cellular adaptation mechanisms.
• This research highlights the intricate balance of DNA synthesis regulation and cellular survival strategies.