{"id":9029,"date":"2024-12-23T11:39:49","date_gmt":"2024-12-23T02:39:49","guid":{"rendered":"https:\/\/www.elsi.jp\/?post_type=news_events&p=9029"},"modified":"2025-10-11T11:38:34","modified_gmt":"2025-10-11T02:38:34","slug":"prebiotic_nucleoside_phosphorylation","status":"publish","type":"news_events","link":"https:\/\/www.elsi.jp\/en\/news_events\/highlights\/2024\/prebiotic_nucleoside_phosphorylation\/","title":{"rendered":"Could a Subsurface Supercritical CO\u2082\u2013Water Two-phase Environment Offer a Solution to the Phosphate Problem and Water Paradox?"},"content":{"rendered":"

Based on the recently proposed Liquid\/Supercritical CO\u2082 Hypothesis, a research team including ELSI\u2019s graduate student Shotaro Tagawa and Associate Professor Kosuke Fujishima successfully simulated a subsurface supercritical CO\u2082\u2013water two-phase environment using a high-pressure reactor. Their study demonstrated the functional significance of this environment in the origin of life. In this setting, water dissolves into the supercritical CO\u2082 phase, enabling concentration of dissolved ions and organic molecules through dehydration. Additionally, water coexisting with the CO\u2082 fluid becomes acidic, facilitating the dissolution of phosphate from phosphate minerals (such as apatite). The researchers confirmed that under such conditions, phosphorylation of nucleoside precursors proceeds at temperatures above 60\u00b0C. This study experimentally validates that the coexistence of supercritical CO\u2082 and water on early Earth could overcome two major challenges\u2014the hydrolysis problem and phosphate depletion\u2014providing a stable source of phosphate-containing organic compounds crucial for the origin of life.<\/strong><\/p>\n

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Figure 1. Schematic diagram representing phosphorylation of organic compounds inside a water droplet surrounded by supercritical CO\u2082 fluids beneath the seafloor. Credit: Takashi TSUJINO, Science Graphics. Co., Ltd.<\/div>\n
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\nIn the context of the early Earth, warm and dry terrestrial hot springs have been considered favourable environments for concentrating simple molecules and promoting reactions that lead to the formation of biomolecules, such as nucleic acids and proteins, utilised by life. Conversely, environments rich in water, like modern hydrothermal vents, have been thought to inhibit concentration of organic and inorganic components as well as promoting the hydrolysis of macromolecules. This paradox, known as the “Water Paradox,” has long been recognized as a critical challenge for the origin of life.<\/p>\n

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In 2022, Takezo Shibuya and Ken Takai from the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) proposed the Liquid\/Supercritical CO\u2082 Hypothesis as a potential solution to this challenge [1]. This hypothesis suggests that CO\u2082 fluids, which are hydrophobic, could act as a drying agent in subsurface environments, similar to the role of the atmosphere in terrestrial settings. Particularly, supercritical CO\u2082, which exists above 31.1\u00b0C, exhibits unique properties of both gases and liquids, creating a highly hydrophobic environment even in water-rich subsurface conditions. Furthermore, the acidic nature of water enriched with CO\u2082 could facilitate the dissolution of phosphate from minerals like apatite, potentially addressing the issue of phosphate scarcity.<\/p>\n

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To investigate these possibilities, an international research team led by Tagawa and Fujishima examined whether a supercritical CO\u2082\u2013water two-phase environment could facilitate the dehydration and concentration of organic compounds and release essential ions through mineral dissolution. The supercritical CO\u2082\u2013water environment was reproduced inside a hydrothermal reactor system and a series of experiments were conducted to validate phosphorylation of nucleosides and the dissolution of phosphate minerals [2].<\/p>\n

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For nucleoside phosphorylation, initially sodium phosphate salt was used as a phosphate source, and urea was added to promote the reaction. Phosphorylation of RNA precursors\u2014uridine, adenosine, cytidine, and guanosine\u2014were confirmed under the supercritical CO\u2082\u2013water conditions. Interestingly, cyclic nucleotides, which are commonly observed in wet-dry experiments under conditions simulating terrestrial hot springs, were not detected. Further investigations on uridine revealed that phosphorylation did not occur in water-only conditions without the presence of the supercritical CO\u2082 phase, highlighting the importance of the two-phase environment. Additionally, the yield of phosphorylated uridine increased with rising temperatures (60\u00b0C\u201394\u00b0C).<\/p>\n

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In the apatite dissolution experiments, it was observed that lower temperature conditions (25\u00b0C) resulted in higher phosphate concentrations dissolved from apatite. When apatite was used as the phosphate source, the phosphorylation of uridine was confirmed, albeit with lower yields compared to using sodium dihydrogen phosphate. These results suggest that the supercritical CO\u2082\u2013water two-phase environment enables phosphate mineral dissolution at lower temperatures, supplying the key resource that facilitates organic phosphorylation at higher temperatures. Observations using a reactor with a glass window<\/a> also revealed water evaporating into the supercritical CO\u2082 phase, indicating that this environment could provide conditions analogous to terrestrial hot spring sites, where molecules are concentrated through dry-up.<\/p>\n

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This study experimentally validates a key functional role of abundant subsurface CO\u2082 environments in prebiotic chemical evolution. It also provides new insights into resolving the long-standing Water Paradox associated with hydrothermal vent theories, thereby advancing our understanding of the origins of life.
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\n[1] Shibuya, T., and Takai, K. (2022).\u00a0Progress in Earth and Planetary Science<\/em>,\u00a09<\/em>(1), 60.
\n[2] Tagawa, S., et al. (2024).\u00a0Astrobiology, 24<\/em>(12), 60. 1151-1165<\/p>\n

 
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Figure 2. Reactants of uridine phosphorylation under different temperature conditions
\nLiquid chromatography analysis of products from the phosphorylation of uridine under various temperature conditions in a supercritical CO\u2082\u2013water environment. The results show that as the temperature increases, the yields of various nucleotide products (UDP*, 5\u2019-UMP, 3\u2019-UMP, 2\u2019-UMP*) also increase. Compounds marked with an asterisk (*) were identified based on mass spectrometry due to the lack of direct comparison with standard substances.
\nReproduced from Tagawa et al., Astrobiology<\/em> 2024.<\/div>\n

 
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Figure 3. Concentration of Phosphate Released from Phosphate Minerals
\nThis graph represents the concentration of phosphate released from the phosphate mineral hydroxyapatite into water under a supercritical CO\u2082\u2013water environment, measured using a phosphate assay kit. Experiments were conducted with and without urea under varying temperature conditions. Error bars indicate the standard error derived from a sample size of n = 3.
\nReproduced from Tagawa et al., Astrobiology<\/em> 2024.<\/div>\n
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Journal<\/td>\nAstrobiology<\/td>\n<\/tr>\n
Title of the paper<\/td>\nPrebiotic Nucleoside Phosphorylation in a Simulated Deep-Sea Supercritical Carbon Dioxide\u2013Water Two-Phase Environment<\/td>\n<\/tr>\n
Authors<\/td>\nShotaro Tagawa1,2,7<\/sup>, Ryota Hatami3,4<\/sup>, Kohei Morino1,2<\/sup>, Shohei Terazawa1,2<\/sup>, Caner Akil5<\/sup>, Krisitin Johnson-Finn6<\/sup>, Takazo Shibuya7<\/sup>, Kosuke Fujishima1,2,8*<\/sup><\/td>\n<\/tr>\n
Affiliations<\/td>\n\n
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  1. Earth-Life Science Institute, Institute of Science Tokyo, Tokyo, Japan<\/li>\n
  2. School of Life Science and Technology, Institute of Science Tokyo, Tokyo, Japan<\/li>\n
  3. Astronomical Science Program, The Graduate University for Advanced Studies, SOKENDAI, Tokyo, Japan<\/li>\n
  4. National Astronomical Observatory of Japan, Mitaka, Japan<\/li>\n
  5. Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom<\/li>\n
  6. Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, New York, USA<\/li>\n
  7. Super-cutting-edge Grand and Advanced Research (SUGAR) Program, Institute for Extra-cutting-edge Science and Technology Avantgarde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan.<\/li>\n
  8. Graduate School of Media and Governance, Keio University, Fujisawa, Japan<\/li>\n<\/ol>\n<\/td>\n<\/tr>\n
DOI<\/td>\n\u00a010.1089\/ast.2024.0016<\/a><\/td>\n<\/tr>\n
Online published date<\/td>\n18 November2024<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n","protected":false},"featured_media":9032,"template":"","news_events_cat":[9],"acf":[],"_links":{"self":[{"href":"https:\/\/www.elsi.jp\/wp-json\/wp\/v2\/news_events\/9029"}],"collection":[{"href":"https:\/\/www.elsi.jp\/wp-json\/wp\/v2\/news_events"}],"about":[{"href":"https:\/\/www.elsi.jp\/wp-json\/wp\/v2\/types\/news_events"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.elsi.jp\/wp-json\/wp\/v2\/media\/9032"}],"wp:attachment":[{"href":"https:\/\/www.elsi.jp\/wp-json\/wp\/v2\/media?parent=9029"}],"wp:term":[{"taxonomy":"news_events_cat","embeddable":true,"href":"https:\/\/www.elsi.jp\/wp-json\/wp\/v2\/news_events_cat?post=9029"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}