How a host cell signalling molecule modifies carbon metabolism in symbionts of the coral Plesiastrea versipora

• Published in: The FEBS journal 2013-05, Vol.280 (9), p.2085-2096
• Main Authors: Grant, Adrienne, People, Julie, Rémond, Marc, Frankland, Sarah, Hinde, Rosalind
• Format: Article
• Language: English
• Subjects: Aiptasia pulchella; Alveolata - metabolism; Alveolata - physiology; Animals; Anthozoa - cytology; Anthozoa - metabolism; Carbohydrate Metabolism; Cell adhesion & migration; Chromatography, Ion Exchange; Coral reefs; Glycerol - metabolism; Heliofungia actiniformis; host cell signalling molecules; Intercellular Signaling Peptides and Proteins - isolation & purification; Intercellular Signaling Peptides and Proteins - metabolism; Marine; Molecules; Photosynthesis; Plesiastrea versipora; Plesiastrea versipora; Pocillopora damicornis; Signal Transduction; Signaling; starch; Symbiodinium; Symbiosis; triacylglycerol; Tridacna maxima
• ISSN: 1742-464X; 1742-4658
• DOI: 10.1111/febs.12233

Cnidarian cell signalling remains poorly understood. This study has expanded our knowledge of the cell signalling molecule host release factor (HRF) from the coral Plesiastrea versipora. We have now confirmed that HRF is present in coral host cells that lack intracellular algae. Previous studies showed that HRF stimulates the release of photosynthetic products (mainly glycerol) from Symbiodinium algae, thus providing the host with carbon; glycerol release was accompanied by reduced synthesis of algal triacylglycerols and starch. In this study, we have shown that supplying glycerol to algae incubated with HRF does not restore normal triacylglycerol and starch synthesis. Release of 14C‐labelled products from algae may continue after photosynthesis ceases, although at a much lower rate. When algae were placed in the dark for 4 h with HRF following 2 h of photosynthesis in seawater, 14C‐labelled products were released, but at ≤ 15% of the amount released during 2 h of photosynthesis with HRF. HRF did not stimulate the release of compounds derived from a nonphotosynthetic source. The response of Symbiodinium from P. versipora to HRF has been compared with the response of Symbiodinium algae from Tridacna maxima, Heliofungia actiniformis, Aiptasia pulchella and Pocillopora damicornis to both their own HRF and to P. versipora HRF. Algae from P. versipora showed the highest response to both P. versipora HRF and to the other hosts’ HRF. Further purification of P. versipora HRF suggests that HRF is a peptide with an acidic pI. We propose that HRF will provide a useful tool for the study of carbon metabolism. All animals and plants use cell signals to regulate nutrition, reproduction and growth. A cell signal produced by the long‐lived coral Plesiastrea versipora, regulates the metabolism of algal carbon produced during photosynthesis, reducing starch and triacylglycerol synthesis. This cell signal is produced by animal cells that lack algae, suggesting it may have a role in both animal and plant biochemistry.