title: The Non-canonical Tetratricopeptide Repeat (TPR) Domain of Fluorescent (FLU) Mediates Complex Formation with Glutamyl-tRNA Reductase.
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 (FLU(TPR)) at 1.45-Å resolution and the complex of the dimeric domain of GluTR bound to FLU(TPR) at 2.4-Å resolution. Three non-canonical TPR motifs of each FLU(TPR) form a concave surface and clamp the helix bundle in the C-terminal dimeric domain of GluTR. We demonstrate that a 2:2 FLU(TPR)-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.
authors.affiliation: From the School of Life Sciences, Anhui University, Hefei, Anhui 230601.
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.affiliation: From the School of Life Sciences, Anhui University, Hefei, Anhui 230601.
authors.forename: Feilong
authors.initials: F
authors.lastname: Zhang
authors.affiliation: the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, and the University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Fang
authors.affiliation: the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, and the University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Xuemin
authors.initials: X
authors.lastname: Chen
authors.affiliation: the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, and.
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Chen
authors.affiliation: the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, and.
authors.forename: Wenxia
authors.initials: W
authors.lastname: Zhang
authors.affiliation: the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, and.
authors.forename: Huai-En
authors.initials: HE
authors.lastname: Dai
authors.affiliation: the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, and.
authors.forename: Rongcheng
authors.initials: R
authors.lastname: Lin
authors.affiliation: the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, and liulin@ibcas.ac.cn.
authors.forename: Lin
authors.initials: L
authors.lastname: Liu
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000622:Aminolevulinic Acid / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D020836:Protein Structure, Quaternary; D020449:Repetitive Sequences, Amino Acid; D017386:Sequence Homology, Amino Acid; D045725:Tetrapyrroles / Q000096:biosynthesis
chemical_list: D029681:Arabidopsis Proteins; C478633:FLU protein, Arabidopsis; D046912:Multiprotein Complexes; D045725:Tetrapyrroles; D000622:Aminolevulinic Acid; D000445:Aldehyde Oxidoreductases; C067282:glutamyl tRNA reductase
keywords: Arabidopsis thaliana; Fluorescent (FLU); biosynthesis; chlorophyll; chlorophyll biosynthesis; crystal structure; protein-protein interaction; tetratricopeptide repeat (TPR)