Decoupled transcript and protein concentrations ensure histone homeostasis in different nutrients

Area of Science:

• Cellular biology
• Molecular biology
• Biochemistry

Background:

• Maintaining protein homeostasis is crucial for cellular function, especially under varying nutrient conditions.
• Nutrients influence cell growth and gene expression, posing challenges for regulating cell cycle-dependent genes like histones.
• Histones are essential for DNA packaging and must be maintained at a precise stoichiometry with DNA.

Purpose of the Study:

• To investigate how budding yeast regulates histone levels to maintain protein homeostasis across different nutrient environments.
• To understand the mechanisms underlying the nutrient-dependent control of histone gene expression and protein production.

Main Methods:

• Quantitative analysis of histone transcript and protein levels in budding yeast under various nutrient conditions.
• Investigation of translational control mechanisms affecting histone synthesis.
• Assessment of the impact of nutrient availability on cell cycle gene regulation.

Main Results:

• Budding yeast downregulates histone transcripts in nutrient-poor conditions to prevent toxic overexpression.
• Constant histone protein levels are maintained through nutrient-specific regulation of translation efficiency.
• This decoupling of transcript and protein abundance allows for flexible yet precise histone production.

Conclusions:

• Budding yeast employs a sophisticated strategy to achieve histone homeostasis by uncoupling mRNA and protein levels.
• Nutrient-dependent translational control is key to balancing rapid histone production during growth with avoiding toxicity in poor nutrient conditions.
• This regulatory mechanism ensures proper histone-to-DNA stoichiometry essential for genome integrity.