Exploring the Roles of Chloroplast GNATs: Acetylation as a Regulatory Mechanism in Photosynthesis and Senescence

• Applicants: Professorin Dr. Iris Finkemeier; Professor Dr. Christian Schmitz-Linneweber
• Subject Area: Plant Biochemistry and Biophysics ; Plant Physiology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 568805223

The AcetylPlast project aims to elucidate the roles of a recently discovered family of plastid-localized GNAT acetyltransferases in regulating photosynthesis, plastid biogenesis, stress acclimation, and senescence. We hypothesize that these enzymes act as dual-function protein modifiers—catalyzing both N-terminal (NTA) and lysine (KA) acetylation—to dynamically modulate plastid function across molecular, cellular, and organismal scales. Building on our discovery of GNAT2’s light-responsive KA activity and its role in regulating photosynthetic performance, we now seek to characterize the functional diversity of plastid GNATs. At the molecular level (WP1), we will investigate how GNATs influence RuBisCO maturation and efficiency through targeted acetylation. At the cellular level (WP2), we will explore how GNAT activity regulates phase separation and plastid RNA metabolism, focusing on acetylation-dependent modulation of RNA-binding proteins such as CP29A. At the organismal level (WP3), we will examine the integration of GNAT activity into stress responses and senescence, including interactions with plastid deacetylases like HDA14. The project is led by internationally recognized experts in plastid biology and protein modification. French (Giglione) and German (Finkemeier, Schmitz-Linneweber) teams bring complementary strengths in enzymology, proteomics, biocondensate biology, and stress physiology. Together, they will apply a multidisciplinary approach using reconstituted systems, plant mutants, and multi-omics tools to determine functions of GNATS for fundamental and emerging questions in plant biology (carbon fixation; sub-compartmentalization). By uncovering the regulatory logic of plastid acetylation, AcetylPlast will provide novel insights into plant adaptability and proteostasis and open new avenues for optimizing photosynthetic performance under changing environmental conditions.

• DFG Programme: Research Grants
• International Connection: France
• Cooperation Partner: Carmela Giglione, Ph.D.