Structural basis of metabolite transport by the chloroplast outer envelope channel OEP21

Triose phosphates (TPs) are the primary products of photosynthetic CO₂ fixation in chloroplasts, which need to be exported into the cytosol across the chloroplast inner envelope (IE) and outer envelope (OE) membranes to sustain plant growth.

A team of researchers around Prof. Franz Hagn unravels the structural and functional properties of OEP21, a major metabolite channel in the chloroplast outer envelope, and show that this porin utilizes a promiscuous mechanism to control the passage of a distinct set of substrates.

These results provide a better understanding of metabolite transport across the chloroplast outer envelope membrane and will facilitate the rational design of optimized transport in engineered food and energy crops for enhanced biomass production.

“With this publication and the obtained structural and functional information, we achieved a breakthrough in the mechanistic understanding of the mode of action of metabolite pores in chloroplasts”, Prof. Franz Hagn, the corresponding author says.

_{Funding information:
This study was supported by the Helmholtz Society (grant no. VG-NG-1035) and the Technical University of Munich, Institute for Advanced Study, funded by the German Excellence Initiative and the European Union Seventh Framework Programme under grant agreement no. 291763, as well as the Center for Integrated Protein Science Munich (CIPS^M).}