Function of the ER located ATP carrier ER-ANT1

• Applicant: Professor Dr. Ekkehard Neuhaus
• Subject Area: Plant Physiology
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 321321777

Plants possess at least two types of ATP transporters, namely the so called NTT (nucleotide transporters) residing in plastids, and several homologous members of the mitochondrial carrier family (MCF) residing in the inner mitochondrial membrane, the inner plastid-envelope membrane, the plasma membrane, the peroxisomal membrane and the Endoplasmic Reticulum (ER) membrane. The ER located adenylate carrier (ER-ANT1) catalyzes ATP/ADP exchange and knock-out mutants (er-ant1) surprisingly exhibit a photorespiratory phenotype. We raised evidence that er-ant1 plants show impaired ability to cope with reactive oxygen species (ROS) released during photorespiration. This observation led to the hypothesis that ROS are causative for the dwarf phenotype of er-ant1 lines when grown under ambient CO2. With help of er-ant1 derived mutants showing improved ROS tolerance we wish to prove this hypothesis. On basis of er-ant1 plants we initiated a forward genetic approach and generated several EMS induced suppressor lines, showing better growth under ambient CO2. We assume that repression of the dwarf phenotype is possible by several independent cellular modifications scavenging ROS in these suppressor lines. To proof this assumption the responsible loci will be identified by using Next Generation Sequencing (NGS) and each genetic modification will be confirmed by directed introduction of corresponding changes in the er-ant1 background. So far the exact involvement of ER-ANT1 (which is located in the ER membrane) in photorespiration (running outside ER) is fully obscure. We expect that detailed molecular analysis of a sufficient number of EMS induced er-ant1 suppressor lines provides today the best (maybe sole) way to clarify this open question on a surprising interaction between ER located processes and photorespiration.

• DFG Programme: Research Grants