Auxiliary factors required for the accumulation and functioning of the thylakoid ATP synthase

• Applicant: Professor Dr. Dario Leister
• Subject Area: Plant Physiology ; Plant Biochemistry and Biophysics
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 261977268

The chloroplast F1Fo-ATP synthase (cpATPase) couples ATP synthesis to the light-driven electrochemical proton gradient and comprise two parts, the membranous CFo subcomplex that is a proton channel and the peripheral CF1 subcomplex that contains the catalytic sites for reversible ATP synthesis. To fully assemble a functional cpATPase complex, various auxiliary factors are needed - either for the expression of the chloroplast-located genes for cpATPase subunits (the atp genes) or for the assembly process itself. While several assembly factors of the F1Fo-ATP synthase are known in prokaryotes and yeast, for plants only the assembly factor ALB4 has been identified yet. In addition, a couple of plant proteins involved in atp gene expression have been described. In this project, we want to characterize two novel auxiliary proteins required for cpATPase biogenesis in the model plant Arabidopsis thaliana. The first one, AtCGL160, appears to be a true assembly factor and interacts physically with subunits of the CFo subcomplex. Interestingly, AtCGL160 contains besides a plant-specific domain also a shorter part, which is related to the prokaryotic Atp1/UncI proteins that have been also brought into connection with ATP synthase assembly. Therefore, we want to clarify the mechanism by which AtCGL160 promotes cpATPase assembly, whether this mechanism is conserved between prokaryotic Atp1/UncI proteins and eukaryotic CGL160 proteins, and reveal the function of the plant-specific part of AtCGL160. The second protein that we have identified to be required for cpATPase biogenesis is AtCGLD11. In contrast to AtCGL160, the AtCGLD11 protein is soluble and displays an mRNA expression pattern that suggests a function in atp gene expression. Therefore, we will characterise the function(s) of AtCGLD11 particularly in atp gene expression, including global approaches that can detect its interactions with any of the entire set of chloroplast genes and transcripts.

• DFG Programme: Research Grants