CO2-dependent migration and relocation of LCIB, a pyrenoid-peripheral protein in Chlamydomonas reinhardtii
| Autor: | Takashi Yamano, Chihana Toyokawa, Hideya Fukuzawa, Toshiki Matsuoka, Daisuke Shimamura |
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| Rok vydání: | 2021 |
| Předmět: |
Chloroplasts
Physiology Chlamydomonas reinhardtii Plant Science Cycloheximide Genes Plant Pyrenoid chemistry.chemical_compound Cell Movement Gene Expression Regulation Plant Genetics Carbonic Anhydrases Plant Proteins biology RuBisCO DCMU Carbon Dioxide Plants Genetically Modified biology.organism_classification Cell biology Chloroplast Chloroplast stroma chemistry Photosynthetic acclimation biology.protein |
| Zdroj: | Plant Physiology. 188:1081-1094 |
| ISSN: | 1532-2548 0032-0889 |
| Popis: | Most microalgae overcome the difficulty of acquiring inorganic carbon (Ci) in aquatic environments by inducing a CO2-concentrating mechanism (CCM). In the green alga Chlamydomonas reinhardtii, two distinct photosynthetic acclimation states have been described under CO2-limiting conditions (low-CO2 [LC] and very low-CO2 [VLC]). LC-inducible protein B (LCIB), structurally characterized as carbonic anhydrase, localizes in the chloroplast stroma under CO2-supplied and LC conditions. In VLC conditions, it migrates to aggregate around the pyrenoid, where the CO2-fixing enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase is enriched. Although the physiological importance of LCIB localization changes in the chloroplast has been shown, factors necessary for the localization changes remain uncertain. Here, we examined the effect of pH, light availability, photosynthetic electron flow, and protein synthesis on the localization changes, along with measuring Ci concentrations. LCIB dispersed or localized in the basal region of the chloroplast stroma at 8.3–15 µM CO2, whereas LCIB migrated toward the pyrenoid at 6.5 µM CO2. Furthermore, LCIB relocated toward the pyrenoid at 2.6–3.4 µM CO2, even in cells in the dark or treated with 3-(3,4-dichlorophenyl)-1,1-dimethylurea and cycloheximide in light. In contrast, in the mutant lacking CCM1, a master regulator of CCM, LCIB remained dispersed even at 4.3 µM CO2. Meanwhile, a simultaneous expression of LCIC, an interacting protein of LCIB, induced the localization of several speckled structures at the pyrenoid periphery. These results suggest that the localization changes of LCIB require LCIC and are controlled by CO2 concentration with ∼7 µM as the boundary. |
| Databáze: | OpenAIRE |
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