Selective loss of photosystem I and formation of tubular thylakoids in heterotrophically grown red alga Cyanidioschyzon merolae
- 120 Downloads
We previously found that glycerol is required for heterotrophic growth in the unicellular red alga Cyanidioschyzon merolae. Here, we analyzed heterotrophically grown cells in more detail. Sugars or other organic substances did not support the growth in the dark. The growth rate was 0.4 divisions day−1 in the presence of 400 mM glycerol, in contrast with 0.5 divisions day−1 in the phototrophic growth. The growth continued until the sixth division. Unlimited heterotrophic growth was possible in the medium containing DCMU and glycerol in the light. Light-activated heterotrophic culture in which cells were irradiated by intermittent light also continued without an apparent limit. In the heterotrophic culture in the dark, chlorophyll content drastically decreased, as a result of inability of dark chlorophyll synthesis. Photosynthetic activity gradually decreased over 10 days, and finally lost after 19 days. Low-temperature fluorescence measurement and immunoblot analysis showed that this decline in photosynthetic activity was mainly due to the loss of Photosystem I, while the levels of Photosystem II and phycobilisomes were maintained. Accumulated triacylglycerol was lost during the heterotrophic growth, while keeping the overall lipid composition. Observation by transmission electron microscopy revealed that a part of thylakoid membranes turned into pentagonal tubular structures, on which five rows of phycobilisomes were aligned. This might be a structure that compactly conserve phycobilisomes and Photosystem II in an inactive state, probably as a stock of carbon and nitrogen. These results suggest that C. merolae has a unique strategy of heterotrophic growth, distinct from those found in other red algae.
KeywordsGlycerol nutrition Heterotrophic growth Red alga Tubular thylakoid
We thank Ms. Megumi Kobayashi, Japan Women’s University, for technical assistance in tomography, Dr. Koichi Kobayashi, Osaka Prefectural University, for technical advice in measurement of low-temperature fluorescence, and Prof. Hajime Wada, University of Tokyo, for discussion on fluorescence measurement.
TM and NM performed all experiments; NN performed tomography; NS conceived the research and performed electron microscopy.
This work was supported in part by Core Research for Evolutional Science and Technology (CREST) from the Japan Science and Technology Agency (JST) and a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan (Grant. No. 17H03715).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
The manuscript has not been submitted elsewhere to other journals for simultaneous consideration. It is an expansion of our previous works, but no materials were re-used. No data have been fabricated or manipulated. No data, text, or theories by others are presented as if they were the author’s own.
Human and animal participants
This research does not involve human participants or animals.
This research does not require informed consent. Consent to submit has been received explicitly from all co-authors.
- Barbier G, Oesterhelt C, Larson MD et al (2005) Comparative genomics of two closely related unicellular thermo-acidophilic red algae, Galdieria sulphuraria and Cyanidioschyzon merolae, reveals the molecular basis of the metabolic flexibility of Galdieria sulphuraria and significant. Plant Physiol 137:460–474. https://doi.org/10.1104/pp.104.051169 CrossRefPubMedPubMedCentralGoogle Scholar
- Fujimori T, Higuchi M, Sato H et al (2005) The mutant of sll1961, which encodes a putative transcriptional regulator, has a defect in regulation of photosystem stoichiometry in the cyanobacterium Synechocystis sp. PCC 6803. Plant Physiol 139:408–416. https://doi.org/10.1104/pp.105.064782 CrossRefPubMedPubMedCentralGoogle Scholar
- Fujiwara T, Misumi O, Tashiro K et al (2009) Periodic gene expression patterns during the highly synchronized cell nucleus and organelle division cycles in the unicellular red alga Cyanidioschyzon merolae. DNA Res 16:59–72. https://doi.org/10.1093/dnares/dsn032 CrossRefPubMedPubMedCentralGoogle Scholar
- Graves DA, Spradlin GM, Greenbaum E (1990) Effect of oxygen on photoautotrophic and heterotrophic growth of Chlamydomonas reinhardtii in an anoxic atmosphere. Photochem Photobiol 52:585–590. https://doi.org/10.1111/j.1751-1097.1990.tb01803.x CrossRefPubMedGoogle Scholar
- Gross W, Schnarrenberger C (1995) Heterotrophic growth of two strains of the acido-thermophilic red alga Galdieria sulphuraria. Plant Cell Physiol 36:633–638. https://doi.org/10.1093/oxfordjournals.pcp.a078803 CrossRefGoogle Scholar
- Imamura S, Terashita M, Ohnuma M et al (2010) Nitrate assimilatory genes and their transcriptional regulation in a unicellular red alga Cyanidioschyzon merolae: genetic evidence for nitrite reduction by a sulfite reductase-like enzyme. Plant Cell Physiol 51:707–717. https://doi.org/10.1093/pcp/pcq043 CrossRefPubMedGoogle Scholar
- Ishikawa M, Fujiwara M, Sonoike K, Sato N (2009) Orthogenomics of photosynthetic organisms: bioinformatic and experimental analysis of chloroplast proteins of endosymbiont origin in arabidopsis and their counterparts in S ynechocystis. Plant Cell Physiol 50:773–788. https://doi.org/10.1093/pcp/pcp027 CrossRefPubMedGoogle Scholar
- Kada S, Koike H, Satoh K et al (2003) Arrest of chlorophyll synthesis and differential decrease of photosystems I and II in a cyanobacterial mutant lacking light-independent protochlorophyllide reductase. Plant Mol Biol 51:225–235. https://doi.org/10.1023/A:1021195226978 CrossRefPubMedGoogle Scholar
- Moriyama T, Mori N, Sato N (2015) Activation of oxidative carbon metabolism by nutritional enrichment by photosynthesis and exogenous organic compounds in the red alga Cyanidioschyzon merolae: evidence for heterotrophic growth. Springerplus 4:559. https://doi.org/10.1186/s40064-015-1365-0 CrossRefPubMedPubMedCentralGoogle Scholar
- Ohnuma M, Yokoyama T, Inouye T et al (2014) Optimization of polyethylene glycol (PEG)-mediated DNA introduction conditions for transient gene expression in the unicellular red alga Cyanidioschyzon merolae. J Gen Appl Microbiol 60:156–159. https://doi.org/10.2323/jgam.60.156 CrossRefPubMedGoogle Scholar
- Raven JA, Johnston AM, MacFarlane JJ (1990) Carbon metabolism. In: Cole KM, Sheath RG (eds) Biology of the red algae. Cambridge University Press, Cambridge, pp 171–202Google Scholar
- Sato N, Moriyama T (2017) Photosynthesis. In: Kuroiwa T, Miyagishima S, Matsunaga S, Sato N, Nozaki H, Tanaka K, Misumi O (eds) Cyanidioschyzon merolae: A new model eukaryote for cell and organelle biology. Springer, Singapore, pp 263–281. https://doi.org/10.1007/978-981-10-6101-1 CrossRefGoogle Scholar
- Smart LB, Anderson SL, McIntosh L (1991) Targeted genetic inactivation of the photosystem I reaction center in the cyanobacterium Synechocystis sp. PCC 6803. EMBO J 10:3289–3296. https://doi.org/10.1002/j.1460-2075.1991.tb04893.x CrossRefPubMedPubMedCentralGoogle Scholar
- van de Meene AML, Sharp WP, McDaniel JH et al (2012) Gross morphological changes in thylakoid membrane structure are associated with photosystem I deletion in Synechocystis sp. PCC 6803. Biochim Biophys Acta—Biomembr 1818:1427–1434. https://doi.org/10.1016/J.BBAMEM.2012.01.019 CrossRefGoogle Scholar