TY - JOUR TI - The GluTR-binding protein is the heme-binding factor for feedback control of glutamyl-tRNA reductase AU - Richter, Andreas S AU - Banse, Claudia AU - Grimm, Bernhard A2 - Hamza, Iqbal A2 - Marletta, Michael A A2 - Hansson, Mats VL - 8 PY - 2019 DA - 2019/06/13 SP - e46300 C1 - eLife 2019;8:e46300 DO - 10.7554/eLife.46300 UR - https://doi.org/10.7554/eLife.46300 AB - Synthesis of 5-aminolevulinic acid (ALA) is the rate-limiting step in tetrapyrrole biosynthesis in land plants. In photosynthetic eukaryotes and many bacteria, glutamyl-tRNA reductase (GluTR) is the most tightly controlled enzyme upstream of ALA. Higher plants possess two GluTR isoforms: GluTR1 is predominantly expressed in green tissue, and GluTR2 is constitutively expressed in all organs. Although proposed long time ago, the molecular mechanism of heme-dependent inhibition of GluTR in planta has remained elusive. Here, we report that accumulation of heme, induced by feeding with ALA, stimulates Clp-protease-dependent degradation of Arabidopsis GluTR1. We demonstrate that binding of heme to the GluTR-binding protein (GBP) inhibits interaction of GBP with the N-terminal regulatory domain of GluTR1, thus making it accessible to the Clp protease. The results presented uncover a functional link between heme content and the post-translational control of GluTR stability, which helps to ensure adequate availability of chlorophyll and heme. KW - tetrapyrrole biosynthesis KW - 5-aminolevulinic acid synthesis KW - GluTR KW - heme KW - posttranslational regulation JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -