Chloroplast Sec14-like 1 (CPSFL1) is essential for normal chloroplast development and affects carotenoid accumulation in Chlamydomonas
| Autor: | Ian McRae, C. Shan Xu, Eva M. Schmid, Harald F. Hess, Tomomi Takeuchi, José G. García-Cerdán, Eva Nogales, Nichakarn Yordduangjun, Ahmed M. Hassan, Kent L. McDonald, Daniel A. Fletcher, Patricia Grob, Krishna K. Niyogi |
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| Rok vydání: | 2020 |
| Předmět: |
0106 biological sciences
0301 basic medicine Chloroplasts Mutant Plant Biology Chlamydomonas reinhardtii macromolecular substances 01 natural sciences 03 medical and health sciences chemistry.chemical_compound Phytoene Protein Domains polycyclic compounds Plastid Carotenoid Phylogeny CRAL-TRIO domain Plant Proteins chemistry.chemical_classification photosynthesis Multidisciplinary biology phytoene Chemistry organic chemicals Chlamydomonas carotenoids food and beverages Biological Sciences biology.organism_classification biological factors Chloroplast phosphatidic acid 030104 developmental biology Biochemistry Carotenoid transport 010606 plant biology & botany |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America, vol 117, iss 22 Proceedings of the National Academy of Sciences of the United States of America |
| ISSN: | 1091-6490 0027-8424 |
| DOI: | 10.1073/pnas.1916948117 |
| Popis: | Significance Carotenoids are essential molecules in oxygenic photoautotrophs, and they fulfill essential requirements for human and animal nutrition. How carotenoid accumulation is regulated in the chloroplast, a cyanobacterium-derived organelle, remains poorly understood, despite significant advancements in identifying enzymes of the carotenoid biosynthetic pathway. This study identifies a role of chloroplast Sec14-like 1 (CPSFL1), a CRAL-TRIO protein of eukaryotic origin, in modulation of carotenoid biosynthesis and accumulation in the chloroplast. The CPSFL1 protein represents an isoprenoid- and carotenoid-binding protein that associates with membranes through interactions with the phospholipid phosphatidic acid. These findings have implications for understanding carotenoid biosynthesis and optimizing algal carotenoid nutritional quality. Plastid isoprenoid-derived carotenoids serve essential roles in chloroplast development and photosynthesis. Although nearly all enzymes that participate in the biosynthesis of carotenoids in plants have been identified, the complement of auxiliary proteins that regulate synthesis, transport, sequestration, and degradation of these molecules and their isoprenoid precursors have not been fully described. To identify such proteins that are necessary for the optimal functioning of oxygenic photosynthesis, we screened a large collection of nonphotosynthetic (acetate-requiring) DNA insertional mutants of Chlamydomonas reinhardtii and isolated cpsfl1. The cpsfl1 mutant is extremely light-sensitive and susceptible to photoinhibition and photobleaching. The CPSFL1 gene encodes a CRAL-TRIO hydrophobic ligand-binding (Sec14) domain protein. Proteins containing this domain are limited to eukaryotes, but some may have been retargeted to function in organelles of endosymbiotic origin. The cpsfl1 mutant showed decreased accumulation of plastidial isoprenoid-derived pigments, especially carotenoids, and whole-cell focused ion-beam scanning-electron microscopy revealed a deficiency of carotenoid-rich chloroplast structures (e.g., eyespot and plastoglobules). The low carotenoid content resulted from impaired biosynthesis at a step prior to phytoene, the committed precursor to carotenoids. The CPSFL1 protein bound phytoene and β-carotene when expressed in Escherichia coli and phosphatidic acid in vitro. We suggest that CPSFL1 is involved in the regulation of phytoene synthesis and carotenoid transport and thereby modulates carotenoid accumulation in the chloroplast. |
| Databáze: | OpenAIRE |
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