Mitochondrial hyper-acetylation induced by an engineered acetyltransferase promotes cellular senescence

Area of Science:

• Biochemistry
• Cell Biology
• Metabolomics

Background:

• Protein acetylation is vital for cellular functions, particularly mitochondrial metabolism.
• Mitochondrial acetylation is poorly understood due to a lack of identified acetyltransferases.
• Sirtuin 3 (SIRT3) is known to deacetylate mitochondrial proteins.

Purpose of the Study:

• To engineer a mitochondria-localized acetyltransferase to investigate the role of protein acetylation in mitochondrial function.
• To explore the physiological relevance and functional consequences of induced mitochondrial hyper-acetylation.

Main Methods:

• Development and mitochondrial matrix localization of an engineered acetyltransferase (eMAT).
• Global proteomic analysis to identify eMAT-mediated acetylation sites.
• Assessment of cellular phenotypes including energy metabolism, cell growth, and senescence.

Main Results:

• eMAT successfully induced global protein lysine acetylation in the mitochondrial matrix, targeting 413 proteins.
• The eMAT-driven acetylation pattern showed significant overlap with previously identified acetylation sites, confirming physiological relevance.
• Induced hyper-acetylation negatively impacted mitochondrial energy metabolism and cell growth, while promoting cellular senescence.
• SIRT3 activity was shown to reverse eMAT-induced hyper-acetylation, restore metabolic function, and prevent senescence.

Conclusions:

• Engineered mitochondrial acetyltransferase (eMAT) provides a tool to study mitochondrial acetylation.
• Mitochondrial hyper-acetylation inhibits energy metabolism and drives cellular senescence.
• SIRT3 plays a critical role in maintaining mitochondrial homeostasis by counteracting hyper-acetylation and preventing senescence.