1. The Non-canonical Tetratricopeptide Repeat (TPR) Domain of Fluorescent (FLU) Mediates Complex Formation with Glutamyl-tRNA Reductase.
- Author
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Min Zhang, Feilong Zhang, Ying Fang, Xuemin Chen, Yuhong Chen, Wenxia Zhang, Huai-En Dai, Rongcheng Lin, and Lin Liu
- Subjects
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GLUTAMYL-tRNA synthetase , *CHLOROPHYLL , *BIOSYNTHESIS , *MEMBRANE proteins , *BIOCHEMICAL research - Abstract
The tetratricopeptide repeat (TPR)-containing protein FLU is a negative regulator of chlorophyll biosynthesis in plants. It directly interacts through its TPR domain with glutamyl-tRNA reductase (GluTR), the rate-limiting enzyme in the formation of δ-aminolevulinic acid (ALA). Delineation of how FLU binds to GluTR is important for understanding the molecular basis for FLU-mediated repression of synthesis of ALA, the universal tetrapyrrole precursor. Here, we characterize the FLU-GluTR interaction by solving the crystal structures of the uncomplexed TPR domain of FLU (FLUTPR) at 1.45-Å resolution and the complex of the dimeric domain of GluTR bound to FLUTPR at 2.4-Å resolution. Three non-canonical TPR motifs of each FLUTPR form a concave surface and clamp the helix bundle in the C-terminal dimeric domain of GluTR. We demonstrate that a 2:2 FLUTPR-GluTR complex is the functional unit for FLU-mediated GluTR regulation and suggest that the formation of the FLU-GluTR complex prevents glutamyl-tRNA, the GluTR substrate, from binding with this enzyme. These results also provide insights into the spatial regulation of ALA synthesis by the membrane-located FLU protein. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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