Characterization of the plant mitochondrial twin arginine translocation pathway

• Applicant: Privatdozent Christopher Carrie, Ph.D.
• Subject Area: Plant Cell and Developmental Biology ; Plant Physiology
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 350182520

• Final Report Year: 2022

Final Report Abstract

Twin arginine translocation (TAT) pathways have been extensively studied in bacteria and chloroplasts for their role in membrane translocation of folded proteins. However, an increasing number of organisms have been found to contain mitochondria-located TAT subunits, including plant mitochondria which contain TAT subunits, though in an unusual arrangement with only TatB and TatC subunits. To date, no confirmed function has been attributed to mitochondrial TAT pathways in any organism. Using a truncation mutant approach, we demonstrate that the plant mitochondrial TatB (MTTATB) is required for complex III biogenesis. More specifically, MTTATB performs at a late stage in complex III biogenesis conveying the translocation of the C-terminus of the Rieske FeS subunit back across the inner membrane. This work confirms that plant mitochondria retained a functional TAT pathway for the Rieske FeS translocation, most likely from the original mitochondrial ancestor. It is hypothesized that the original mitochondria contained a bacteria-derived TAT pathway required for at least the Rieske FeS translocation. In several eukaryotic lineages this mitochondrial TAT pathway was lost and replaced by BCS1. Interestingly, plant mitochondria appear to assemble complex III in the same subunit order as yeast and mammals but in contrast use bacteria-like assembly factors for this process.

Publications

• (2017). The PPR protein SLOW GROWTH 4 is involved in editing of nad4 and affects the splicing of nad2 intron 1. Plant Mol Biol 93, 355-368
  Weissenberger, S., Soll, J., and Carrie, C.
  
• (2017). To Mia or not to Mia: stepwise evolution of the mitochondrial intermembrane space disulfide relay. BMC Biol 15, 119
  Carrie, C., and Soll, J.
  
• (2018). Plant Mitochondrial Inner Membrane Protein Insertion. Int J Mol Sci 19
  Kolli, R., Soll, J., and Carrie, C.
  
• (2019). Assembly of the Complexes of the Oxidative Phosphorylation System in Land Plant Mitochondria. Annu Rev Plant Biol 70, 23-50
  Meyer, E.H., Welchen, E., and Carrie, C.
  
• (2019). OXA2b is Crucial for Proper Membrane Insertion of COX2 during Biogenesis of Complex IV in Plant Mitochondria. Plant Physiol 179, 601-615
  Kolli, R., Soll, J., and Carrie, C.
  
• (2020). The OXA2a Insertase of Arabidopsis Is Required for Cytochrome c Maturation. Plant Physiol 184, 1042-1055
  Kolli, R., Engstler, C., Akbas, S., Mower, J.P., Soll, J., and Carrie, C.
  
• (2020). The Plant Mitochondrial TAT Pathway Is Essential for Complex III Biogenesis. Curr Biol 30, 840-853 e845
  Schafer, K., Kunzler, P., Schneider, K., Klingl, A., Eubel, H., and Carrie, C.
  
• (2022). Assessment of Mitochondrial Protein Topology and Membrane Insertion. Methods Mol Biol 2363, 165-181
  Schafer, K., Engstler, C., Dischinger, K., and Carrie, C.