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Cohen ZR, Todd ZR, Maibaum L, Catling DC, Black RA. Stabilization of Prebiotic Vesicles by Peptides Depends on Sequence and Chirality: A Mechanism for Selection of Protocell-Associated Peptides. Langmuir 2024; 40:8971-8980. [PMID: 38629792 DOI: 10.1021/acs.langmuir.4c00150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/01/2024]
Abstract
Cells require oligonucleotides and polypeptides with specific, homochiral sequences to perform essential functions, but it is unclear how such oligomers were selected from random sequences at the origin of life. Cells were probably preceded by simple compartments such as fatty acid vesicles, and oligomers that increased the stability, growth, or division of vesicles could have thereby increased in frequency. We therefore tested whether prebiotic peptides alter the stability or growth of vesicles composed of a prebiotic fatty acid. We find that three of 15 dipeptides tested reduce salt-induced flocculation of vesicles. All three contain leucine, and increasing their length increases the efficacy. Also, leucine-leucine but not alanine-alanine increases the size of vesicles grown by multiple additions of micelles. In a molecular simulation, leucine-leucine docks to the membrane, with the side chains inserted into the hydrophobic core of the bilayer, while alanine-alanine fails to dock. Finally, the heterochiral forms of leucine-leucine, at a high concentration, rapidly shrink the vesicles and make them leakier and less stable to high pH than the homochiral forms do. Thus, prebiotic peptide-membrane interactions influence the flocculation, growth, size, leakiness, and pH stability of prebiotic vesicles, with differential effects due to sequence, length, and chirality. These differences could lead to a population of vesicles enriched for peptides with beneficial sequence and chirality, beginning selection for the functional oligomers that underpin life.
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Affiliation(s)
- Zachary R Cohen
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Zoe R Todd
- Department of Earth and Space Science, University of Washington, Seattle, Washington 98195, United States
| | - Lutz Maibaum
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - David C Catling
- Department of Earth and Space Science, University of Washington, Seattle, Washington 98195, United States
| | - Roy A Black
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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2
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Cohen ZR, Ding D, Zhou L, DasGupta S, Haas S, Sinclair KP, Todd ZR, Black RA, Szostak JW, Catling DC. Natural soda lakes provide compatible conditions for RNA and membrane function that could have enabled the origin of life. PNAS Nexus 2024; 3:pgae084. [PMID: 38505692 PMCID: PMC10949909 DOI: 10.1093/pnasnexus/pgae084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 01/31/2024] [Indexed: 03/21/2024]
Abstract
The origin of life likely occurred within environments that concentrated cellular precursors and enabled their co-assembly into cells. Soda lakes (those dominated by Na+ ions and carbonate species) can concentrate precursors of RNA and membranes, such as phosphate, cyanide, and fatty acids. Subsequent assembly of RNA and membranes into cells is a long-standing problem because RNA function requires divalent cations, e.g. Mg2+, but Mg2+ disrupts fatty acid membranes. The low solubility of Mg-containing carbonates limits soda lakes to moderate Mg2+ concentrations (∼1 mM), so we investigated whether both RNAs and membranes function within these lakes. We collected water from Last Chance Lake and Goodenough Lake in Canada. Because we sampled after seasonal evaporation, the lake water contained ∼1 M Na+ and ∼1 mM Mg2+ near pH 10. In the laboratory, nonenzymatic, RNA-templated polymerization of 2-aminoimidazole-activated ribonucleotides occurred at comparable rates in lake water and standard laboratory conditions (50 mM MgCl2, pH 8). Additionally, we found that a ligase ribozyme that uses oligonucleotide substrates activated with 2-aminoimidazole was active in lake water after adjusting pH from ∼10 to 9. We also observed that decanoic acid and decanol assembled into vesicles in a dilute solution that resembled lake water after seasonal rains, and that those vesicles retained encapsulated solutes despite salt-induced flocculation when the external solution was replaced with dry-season lake water. By identifying compatible conditions for nonenzymatic and ribozyme-catalyzed RNA assembly, and for encapsulation by membranes, our results suggest that soda lakes could have enabled cellular life to emerge on Earth, and perhaps elsewhere.
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Affiliation(s)
- Zachary R Cohen
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
- Astrobiology Program, University of Washington, Seattle, WA 98195, USA
| | - Dian Ding
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Lijun Zhou
- Department of Biochemistry and Biophysics and Penn Institute for RNA Innovation, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Saurja DasGupta
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Sebastian Haas
- Astrobiology Program, University of Washington, Seattle, WA 98195, USA
- Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA
| | - Kimberly P Sinclair
- Astrobiology Program, University of Washington, Seattle, WA 98195, USA
- Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA
| | - Zoe R Todd
- Astrobiology Program, University of Washington, Seattle, WA 98195, USA
- Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA
- Department of Chemistry and Department of Astronomy, University of Wisconsin, Madison, WI 53706, USA
| | - Roy A Black
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
- Astrobiology Program, University of Washington, Seattle, WA 98195, USA
| | - Jack W Szostak
- Howard Hughes Medical Institute, Department of Chemistry, University of Chicago, Chicago, IL 60637, USA
| | - David C Catling
- Astrobiology Program, University of Washington, Seattle, WA 98195, USA
- Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA
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3
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Schaible MJ, Szeinbaum N, Bozdag GO, Chou L, Grefenstette N, Colón-Santos S, Rodriguez LE, Styczinski MJ, Thweatt JL, Todd ZR, Vázquez-Salazar A, Adams A, Araújo MN, Altair T, Borges S, Burton D, Campillo-Balderas JA, Cangi EM, Caro T, Catalano E, Chen K, Conlin PL, Cooper ZS, Fisher TM, Fos SM, Garcia A, Glaser DM, Harman CE, Hermis NY, Hooks M, Johnson-Finn K, Lehmer O, Hernández-Morales R, Hughson KHG, Jácome R, Jia TZ, Marlow JJ, McKaig J, Mierzejewski V, Muñoz-Velasco I, Nural C, Oliver GC, Penev PI, Raj CG, Roche TP, Sabuda MC, Schaible GA, Sevgen S, Sinhadc P, Steller LH, Stelmach K, Tarnas J, Tavares F, Trubl G, Vidaurri M, Vincent L, Weber JM, Weng MM, Wilpiszeki RL, Young A. Chapter 1: The Astrobiology Primer 3.0. Astrobiology 2024; 24:S4-S39. [PMID: 38498816 DOI: 10.1089/ast.2021.0129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
The Astrobiology Primer 3.0 (ABP3.0) is a concise introduction to the field of astrobiology for students and others who are new to the field of astrobiology. It provides an entry into the broader materials in this supplementary issue of Astrobiology and an overview of the investigations and driving hypotheses that make up this interdisciplinary field. The content of this chapter was adapted from the other 10 articles in this supplementary issue and thus represents the contribution of all the authors who worked on these introductory articles. The content of this chapter is not exhaustive and represents the topics that the authors found to be the most important and compelling in a dynamic and changing field.
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Affiliation(s)
- Micah J Schaible
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Nadia Szeinbaum
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - G Ozan Bozdag
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Luoth Chou
- NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- Center for Space Sciences and Technology, University of Maryland, Baltimore, Maryland, USA
- Georgetown University, Washington DC, USA
| | - Natalie Grefenstette
- Santa Fe Institute, Santa Fe, New Mexico, USA
- Blue Marble Space Institute of Science, Seattle, Washington, USA
| | - Stephanie Colón-Santos
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Wisconsin, USA
- Department of Botany, University of Wisconsin-Madison, Wisconsin, USA
| | - Laura E Rodriguez
- Lunar and Planetary Institute, Universities Space Research Association, Houston, Texas, USA
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - M J Styczinski
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- University of Washington, Seattle, Washington, USA
| | - Jennifer L Thweatt
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, Pennsylvania, USA
| | - Zoe R Todd
- Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
| | - Alberto Vázquez-Salazar
- Departamento de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Department of Chemical and Biomolecular Engineering, University of California Los Angeles, California, USA
| | - Alyssa Adams
- Center for Space Sciences and Technology, University of Maryland, Baltimore, Maryland, USA
| | - M N Araújo
- Biochemistry Department, University of São Paulo, São Carlos, Brazil
| | - Thiago Altair
- Institute of Chemistry of São Carlos, Universidade de São Paulo, São Carlos, Brazil
- Department of Chemistry, College of the Atlantic, Bar Harbor, Maine, USA
| | | | - Dana Burton
- Department of Anthropology, George Washington University, Washington DC, USA
| | | | - Eryn M Cangi
- Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, Colorado, USA
| | - Tristan Caro
- Department of Geological Sciences, University of Colorado Boulder, Boulder, Colorado, USA
| | - Enrico Catalano
- Sant'Anna School of Advanced Studies, The BioRobotics Institute, Pisa, Italy
| | - Kimberly Chen
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Peter L Conlin
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Z S Cooper
- Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
| | - Theresa M Fisher
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
| | - Santiago Mestre Fos
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Amanda Garcia
- Department of Bacteriology, University of Wisconsin-Madison, Wisconsin, USA
| | - D M Glaser
- Arizona State University, Tempe, Arizona, USA
| | - Chester E Harman
- Departamento de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Ninos Y Hermis
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- Department of Physics and Space Sciences, University of Granada, Granada, Spain
| | - M Hooks
- NASA Johnson Space Center, Houston, Texas, USA
| | - K Johnson-Finn
- Earth-Life Science Institute, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, Japan
- Rensselaer Polytechnic Institute, Troy, New York, USA
| | - Owen Lehmer
- Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
| | - Ricardo Hernández-Morales
- Departamento de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Kynan H G Hughson
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Rodrigo Jácome
- Departamento de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Tony Z Jia
- Blue Marble Space Institute of Science, Seattle, Washington, USA
- Earth-Life Science Institute, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, Japan
| | - Jeffrey J Marlow
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - Jordan McKaig
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Veronica Mierzejewski
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
| | - Israel Muñoz-Velasco
- Departamento de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Departamento de Biología Celular, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Ceren Nural
- Istanbul Technical University, Istanbul, Turkey
| | - Gina C Oliver
- Department of Geology, San Bernardino Valley College, San Bernardino, California, USA
| | - Petar I Penev
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Chinmayee Govinda Raj
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Tyler P Roche
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Mary C Sabuda
- Department of Earth and Environmental Sciences, University of Minnesota-Twin Cities, Minneapolis, Minnesota, USA
- Biotechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - George A Schaible
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - Serhat Sevgen
- Blue Marble Space Institute of Science, Seattle, Washington, USA
- Institute of Marine Sciences, Middle East Technical University, Erdemli, Mersin, Turkey
| | - Pritvik Sinhadc
- BEYOND: Center For Fundamental Concepts in Science, Arizona State University, Arizona, USA
- Dubai College, Dubai, United Arab Emirates
| | - Luke H Steller
- Australian Centre for Astrobiology, and School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington, Australia
| | - Kamil Stelmach
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - J Tarnas
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Frank Tavares
- Space Enabled Research Group, MIT Media Lab, Cambridge, Massachusetts, USA
| | - Gareth Trubl
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California, USA
| | - Monica Vidaurri
- Center for Space Sciences and Technology, University of Maryland, Baltimore, Maryland, USA
- Department of Physics and Astronomy, Howard University, Washington DC, USA
| | - Lena Vincent
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Wisconsin, USA
| | - Jessica M Weber
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | | | | | - Amber Young
- NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- Northern Arizona University, Flagstaff, Arizona, USA
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4
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Schaible MJ, Todd ZR, Cangi EM, Harman CE, Hughson KHG, Stelmach K. Chapter 3: The Origins and Evolution of Planetary Systems. Astrobiology 2024; 24:S57-S75. [PMID: 38498821 DOI: 10.1089/ast.2021.0127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
The materials that form the diverse chemicals and structures on Earth-from mountains to oceans and biological organisms-all originated in a universe dominated by hydrogen and helium. Over billions of years, the composition and structure of the galaxies and stars evolved, and the elements of life, CHONPS, were formed through nucleosynthesis in stellar cores. Climactic events such as supernovae and stellar collisions produced heavier elements and spread them throughout the cosmos, often to be incorporated into new, more metal-rich stars. Stars typically form in molecular clouds containing small amounts of dust through the collapse of a high-density core. The surrounding nebular material is then pulled into a protoplanetary disk, from which planets, moons, asteroids, and comets eventually accrete. During the accretion of planetary systems, turbulent mixing can expose matter to a variety of different thermal and radiative environments. Chemical and physical changes in planetary system materials occur before and throughout the process of accretion, though many factors such as distance from the star, impact history, and level of heating experienced combine to ultimately determine the final geophysical characteristics. In Earth's planetary system, called the Solar System, after the orbits of the planets had settled into their current configuration, large impacts became rare, and the composition of and relative positions of objects became largely fixed. Further evolution of the respective chemical and physical environments of the planets-geosphere, hydrosphere, and atmosphere-then became dependent on their local geochemistry, their atmospheric interactions with solar radiation, and smaller asteroid impacts. On Earth, the presence of land, air, and water, along with an abundance of important geophysical and geochemical phenomena, led to a habitable planet where conditions were right for life to thrive.
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Affiliation(s)
- Micah J Schaible
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Zoe R Todd
- Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
| | - Eryn M Cangi
- Department of Astrophysical and Planetary Sciences, University of Colorado Boulder, Boulder, Colorado, USA
| | | | - Kynan H G Hughson
- School of Earth and Atmospheric Science, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Kamil Stelmach
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
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5
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Todd ZR, Wogan NF, Catling DC. Favorable Environments for the Formation of Ferrocyanide, a Potentially Critical Reagent for Origins of Life. ACS Earth Space Chem 2024; 8:221-229. [PMID: 38379837 PMCID: PMC10875668 DOI: 10.1021/acsearthspacechem.3c00213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 01/07/2024] [Accepted: 01/08/2024] [Indexed: 02/22/2024]
Abstract
Cyanide and its derivatives play important roles in prebiotic chemistry through a variety of possible mechanisms. In particular, cyanide has been shown to allow for the synthesis of ribonucleotides and amino acids. Although dissolved hydrogen cyanide can be lost as a gas or undergo hydrolysis reactions, cyanide can also potentially be stored and stockpiled as ferrocyanide (Fe(CN)6-4), which is more stable. Furthermore, ferrocyanide aids in some prebiotic synthetic reactions. Here, we investigate the formation rates and yields of ferrocyanide as a function of various environmental parameters, such as the pH, temperature, and concentration. We find that ferrocyanide formation rates and yields are optimal at slightly alkaline conditions (pH 8-9) and moderate temperatures (≈20-30 °C). Given the wide range of possible lake environments likely available on early Earth, our results help to constrain the environmental conditions that would favor cyanide- and ferrocyanide-based prebiotic chemistries. We construct lake box models and find that ferrocyanide may be able to form and reach significant concentrations for prebiotic chemistry on the time scale of years under favorable conditions.
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Affiliation(s)
- Zoe R. Todd
- Department
of Earth and Space Sciences, University
of Washington, Seattle, Washington 98195, United States
- Departments
of Chemistry and Astronomy, University of
Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Nicholas F. Wogan
- Department
of Earth and Space Sciences, University
of Washington, Seattle, Washington 98195, United States
| | - David C. Catling
- Department
of Earth and Space Sciences, University
of Washington, Seattle, Washington 98195, United States
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6
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Cohen ZR, Todd ZR, Wogan N, Black RA, Keller SL, Catling DC. Plausible Sources of Membrane-Forming Fatty Acids on the Early Earth: A Review of the Literature and an Estimation of Amounts. ACS Earth Space Chem 2023; 7:11-27. [PMID: 36704178 PMCID: PMC9869395 DOI: 10.1021/acsearthspacechem.2c00168%20] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 10/18/2022] [Accepted: 10/24/2022] [Indexed: 06/16/2023]
Abstract
The first cells were plausibly bounded by membranes assembled from fatty acids with at least 8 carbons. Although the presence of fatty acids on the early Earth is widely assumed within the astrobiology community, there is no consensus regarding their origin and abundance. In this Review, we highlight three possible sources of fatty acids: (1) delivery by carbonaceous meteorites, (2) synthesis on metals delivered by impactors, and (3) electrochemical synthesis by spark discharges. We also discuss fatty acid synthesis by UV or particle irradiation, gas-phase ion-molecule reactions, and aqueous redox reactions. We compare estimates for the total mass of fatty acids supplied to Earth by each source during the Hadean eon after an extremely massive asteroid impact that would have reset Earth's fatty acid inventory. We find that synthesis on iron-rich surfaces derived from the massive impactor in contact with an impact-generated reducing atmosphere could have contributed ∼102 times more total mass of fatty acids than subsequent delivery by either carbonaceous meteorites or electrochemical synthesis. Additionally, we estimate that a single carbonaceous meteorite would not deliver a high enough concentration of fatty acids (∼15 mM for decanoic acid) into an existing body of water on the Earth's surface to spontaneously form membranes unless the fatty acids were further concentrated by another mechanism, such as subsequent evaporation of the water. Our estimates rely heavily on various assumptions, leading to significant uncertainties; nevertheless, these estimates provide rough order-of-magnitude comparisons of various sources of fatty acids on the early Earth. We also suggest specific experiments to improve future estimates. Our calculations support the view that fatty acids would have been available on the early Earth. Further investigation is needed to assess the mechanisms by which fatty acids could have been concentrated sufficiently to assemble into membranes during the origin of life.
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Affiliation(s)
- Zachary R. Cohen
- Department
of Chemistry, Department of Earth and Space Sciences, and Astrobiology Program, University of Washington, Seattle, Washington 98195, United States
| | - Zoe R. Todd
- Department
of Chemistry, Department of Earth and Space Sciences, and Astrobiology Program, University of Washington, Seattle, Washington 98195, United States
| | - Nicholas Wogan
- Department
of Chemistry, Department of Earth and Space Sciences, and Astrobiology Program, University of Washington, Seattle, Washington 98195, United States
| | - Roy A. Black
- Department
of Chemistry, Department of Earth and Space Sciences, and Astrobiology Program, University of Washington, Seattle, Washington 98195, United States
| | - Sarah L. Keller
- Department
of Chemistry, Department of Earth and Space Sciences, and Astrobiology Program, University of Washington, Seattle, Washington 98195, United States
| | - David C. Catling
- Department
of Chemistry, Department of Earth and Space Sciences, and Astrobiology Program, University of Washington, Seattle, Washington 98195, United States
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7
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Cohen ZR, Todd ZR, Wogan N, Black RA, Keller SL, Catling DC. Plausible Sources of Membrane-Forming Fatty Acids on the Early Earth: A Review of the Literature and an Estimation of Amounts. ACS Earth Space Chem 2023; 7:11-27. [PMID: 36704178 PMCID: PMC9869395 DOI: 10.1021/acsearthspacechem.2c00168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 10/18/2022] [Accepted: 10/24/2022] [Indexed: 06/18/2023]
Abstract
The first cells were plausibly bounded by membranes assembled from fatty acids with at least 8 carbons. Although the presence of fatty acids on the early Earth is widely assumed within the astrobiology community, there is no consensus regarding their origin and abundance. In this Review, we highlight three possible sources of fatty acids: (1) delivery by carbonaceous meteorites, (2) synthesis on metals delivered by impactors, and (3) electrochemical synthesis by spark discharges. We also discuss fatty acid synthesis by UV or particle irradiation, gas-phase ion-molecule reactions, and aqueous redox reactions. We compare estimates for the total mass of fatty acids supplied to Earth by each source during the Hadean eon after an extremely massive asteroid impact that would have reset Earth's fatty acid inventory. We find that synthesis on iron-rich surfaces derived from the massive impactor in contact with an impact-generated reducing atmosphere could have contributed ∼102 times more total mass of fatty acids than subsequent delivery by either carbonaceous meteorites or electrochemical synthesis. Additionally, we estimate that a single carbonaceous meteorite would not deliver a high enough concentration of fatty acids (∼15 mM for decanoic acid) into an existing body of water on the Earth's surface to spontaneously form membranes unless the fatty acids were further concentrated by another mechanism, such as subsequent evaporation of the water. Our estimates rely heavily on various assumptions, leading to significant uncertainties; nevertheless, these estimates provide rough order-of-magnitude comparisons of various sources of fatty acids on the early Earth. We also suggest specific experiments to improve future estimates. Our calculations support the view that fatty acids would have been available on the early Earth. Further investigation is needed to assess the mechanisms by which fatty acids could have been concentrated sufficiently to assemble into membranes during the origin of life.
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Affiliation(s)
- Zachary R. Cohen
- Department
of Chemistry, Department of Earth and Space Sciences, and Astrobiology Program, University of Washington, Seattle, Washington 98195, United States
| | - Zoe R. Todd
- Department
of Chemistry, Department of Earth and Space Sciences, and Astrobiology Program, University of Washington, Seattle, Washington 98195, United States
| | - Nicholas Wogan
- Department
of Chemistry, Department of Earth and Space Sciences, and Astrobiology Program, University of Washington, Seattle, Washington 98195, United States
| | - Roy A. Black
- Department
of Chemistry, Department of Earth and Space Sciences, and Astrobiology Program, University of Washington, Seattle, Washington 98195, United States
| | - Sarah L. Keller
- Department
of Chemistry, Department of Earth and Space Sciences, and Astrobiology Program, University of Washington, Seattle, Washington 98195, United States
| | - David C. Catling
- Department
of Chemistry, Department of Earth and Space Sciences, and Astrobiology Program, University of Washington, Seattle, Washington 98195, United States
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8
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Todd ZR, Cohen ZR, Catling DC, Keller SL, Black RA. Growth of Prebiotically Plausible Fatty Acid Vesicles Proceeds in the Presence of Prebiotic Amino Acids, Dipeptides, Sugars, and Nucleic Acid Components. Langmuir 2022; 38:15106-15112. [PMID: 36445982 PMCID: PMC9753748 DOI: 10.1021/acs.langmuir.2c02118] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 11/02/2022] [Indexed: 06/16/2023]
Abstract
Fatty acid vesicles may have played a role in the origin of life as a major structural component of protocells, with the potential for encapsulation of genetic materials. Vesicles that grew and divided more rapidly than other vesicles could have had a selective advantage. Fatty acid vesicles grow by incorporating additional fatty acids from micelles, and certain prebiotic molecules (e.g., sugars, nucleobases, and amino acids) can bind to fatty acid vesicles and stabilize them. Here, we investigated whether the presence of a variety of biomolecules affects the overall growth of vesicles composed of decanoic acid, a prebiotically plausible fatty acid, upon micelle addition. We tested 31 molecules, including 15 dipeptides, 7 amino acids, 6 nucleobases or nucleosides, and 3 sugars. We find that the initial radius and final radius of vesicles are largely unaffected by the presence of the additional compounds. However, three dipeptides enhanced the initial rates of growth compared to control vesicles with no small molecules added; another three dipeptides decreased the initial rates of growth. We conclude that vesicles can indeed grow in the presence of a wide range of molecules likely to have been involved in the origin of life. These results imply that vesicles would have been able to grow in complex and heterogeneous chemical environments. We find that the molecules that enhance the initial growth rate tend to have hydrophobic groups (e.g., leucine), which may interact with the lipid membrane to affect growth rate; furthermore, the molecules that cause the largest decrease in initial growth rate are dipeptides containing a serine residue, which contains a hydroxyl group that could potentially hydrogen-bond with the fatty acid carboxylate groups.
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Affiliation(s)
- Zoe R. Todd
- Department
of Earth and Space Sciences, University
of Washington, Seattle, Washington98195, United States
| | - Zachary R. Cohen
- Department
of Chemistry, University of Washington, Seattle, Washington98195, United States
| | - David C. Catling
- Department
of Earth and Space Sciences, University
of Washington, Seattle, Washington98195, United States
| | - Sarah L. Keller
- Department
of Chemistry, University of Washington, Seattle, Washington98195, United States
| | - Roy A. Black
- Department
of Chemistry, University of Washington, Seattle, Washington98195, United States
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9
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Cohen ZR, Todd ZR, Catling DC, Black RA, Keller SL. Prebiotic Vesicles Retain Solutes and Grow by Micelle Addition after Brief Cooling below the Membrane Melting Temperature. Langmuir 2022; 38:13407-13413. [PMID: 36278967 DOI: 10.1021/acs.langmuir.2c01842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Replication of RNA genomes within membrane vesicles may have been a critical step in the development of protocells on the early Earth. Cold temperatures near 0 °C improve the stability of RNA and allow efficient copying, while some climate models suggest a cold early Earth, so the first protocells may have arisen in cold-temperature environments. However, at cold temperatures, saturated fatty acids, which would have been available on the early Earth, form gel-phase membranes that are rigid and restrict mobility within the bilayer. Two primary roles of protocell membranes are to encapsulate solutes and to grow by incorporating additional fatty acids from the environment. We test here whether fatty acid membranes in the gel phase accomplish these roles. We find that gel-phase membranes of 10-carbon amphiphiles near 0 °C encapsulate aqueous dye molecules as efficiently as fluid-phase membranes do, but the contents are released if the aqueous solution is frozen at -20 °C. Gel-phase membranes do not grow measurably by micelle addition, but growth resumes when membranes are warmed above the gel-liquid transition temperature. We find that longer, 12-carbon amphiphiles do not retain encapsulated contents near 0 °C. Together, our results suggest that protocells could have developed within environments that experience temporary cooling below the membrane melting temperature, and that membranes composed of relatively short-chain fatty acids would encapsulate solutes more efficiently as temperatures approached 0 °C.
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10
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Abstract
Ultraviolet (UV) light plays a key role in surficial theories of the origin of life, and numerous studies have focused on constraining the atmospheric transmission of UV radiation on early Earth. However, the UV transmission of the natural waters in which origins-of-life chemistry (prebiotic chemistry) is postulated to have occurred is poorly constrained. In this work, we combine laboratory and literature-derived absorption spectra of potential aqueous-phase prebiotic UV absorbers with literature estimates of their concentrations on early Earth to constrain the prebiotic UV environment in marine and terrestrial natural waters, and we consider the implications for prebiotic chemistry. We find that prebiotic freshwaters were largely transparent in the UV, contrary to assumptions in some models of prebiotic chemistry. Some waters, such as high-salinity waters like carbonate lakes, may be deficient in shortwave (≤220 nm) UV flux. More dramatically, ferrous waters can be strongly UV-shielded, particularly if the Fe2+ forms highly UV-absorbent species such as FeCN64-. Such waters may be compelling venues for UV-averse origin-of-life scenarios but are unfavorable for some UV-dependent prebiotic chemistries. UV light can trigger photochemistry even if attenuated through photochemical transformations of the absorber (e.g., eaq- production from halide irradiation), which may have both constructive and destructive effects for prebiotic syntheses. Prebiotic chemistries that invoke waters that contain such absorbers must self-consistently account for the chemical effects of these transformations. The speciation and abundance of Fe2+ in natural waters on early Earth is a major uncertainty and should be prioritized for further investigation, as it played a major role in UV transmission in prebiotic natural waters.
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Affiliation(s)
- Sukrit Ranjan
- Department of Earth, Atmospheric & Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Physics and Astronomy, Center for Interdisciplinary Exploration and Research in Astrophysics, Northwestern University, Evanston, Illinois, USA
- Blue Marble Space Institute of Science, Seattle, Washington, USA
- Address correspondence to: Sukrit Ranjan, Department of Physics and Astronomy, Center for Interdisciplinary Exploration and Research in Astrophysics, Northwestern University, 1800 Sherman Avenue, 6th Floor, Evanston, IL 60601, USA
| | - Corinna L. Kufner
- Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA
| | | | - Zoe R. Todd
- Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA
- Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
| | - Azra Haseki
- Department of Earth, Atmospheric & Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Harvard College, Cambridge, Massachusetts, USA
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11
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Janicki M, Kufner CL, Todd ZR, Kim SC, O’Flaherty DK, Szostak JW, Šponer J, Góra RW, Sasselov DD, Szabla R. Ribose Alters the Photochemical Properties of the Nucleobase in Thionated Nucleosides. J Phys Chem Lett 2021; 12:6707-6713. [PMID: 34260253 PMCID: PMC9634911 DOI: 10.1021/acs.jpclett.1c01384] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Substitution of exocyclic oxygen with sulfur was shown to substantially influence the properties of RNA/DNA bases, which are crucial for prebiotic chemistry and photodynamic therapies. Upon UV irradiation, thionucleobases were shown to efficiently populate triplet excited states and can be involved in characteristic photochemistry or generation of singlet oxygen. Here, we show that the photochemistry of a thionucleobase can be considerably modified in a nucleoside, that is, by the presence of ribose. Our transient absorption spectroscopy experiments demonstrate that thiocytosine exhibits 5 times longer excited-state lifetime and different excited-state absorption features than thiocytidine. On the basis of accurate quantum chemical simulations, we assign these differences to the dominant population of a shorter-lived triplet nπ* state in the nucleoside and longer-lived triplet ππ* states in the nucleobase. This explains the distinctive photoanomerziation of thiocytidine and indicates that the nucleoside will be a less efficient phototherapeutic agent with regard to singlet oxygen generation.
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Affiliation(s)
- Mikołaj
J. Janicki
- Department
of Physical and Quantum Chemistry, Faculty of Chemistry, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego
27, 50-370 Wrocław, Poland
| | - Corinna L. Kufner
- Department
of Astronomy, Harvard-Smithsonian Center
for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, United States
| | - Zoe R. Todd
- Department
of Astronomy, Harvard-Smithsonian Center
for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, United States
| | - Seohyun C. Kim
- Howard
Hughes Medical Institute, Department of Molecular Biology and Center
for Computational and Integrative Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, Massachusetts 02114, United States
| | - Derek K. O’Flaherty
- Howard
Hughes Medical Institute, Department of Molecular Biology and Center
for Computational and Integrative Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, Massachusetts 02114, United States
| | - Jack W. Szostak
- Howard
Hughes Medical Institute, Department of Molecular Biology and Center
for Computational and Integrative Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, Massachusetts 02114, United States
| | - Jiří Šponer
- Institute
of Biophysics, Czech Academy of Sciences, Královopolská 135, 61265 Brno, Czech
Republic
- Regional
Centre of Advanced Technologies and Materials, Czech Advanced Technology
and Research Institute (CATRIN), Palacky
University Olomouc, Slechtitelu
241/27, 783 71 Olomouc-Holice, Czech Republic
| | - Robert W. Góra
- Department
of Physical and Quantum Chemistry, Faculty of Chemistry, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego
27, 50-370 Wrocław, Poland
| | - Dimitar D. Sasselov
- Department
of Astronomy, Harvard-Smithsonian Center
for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, United States
| | - Rafał Szabla
- EaStCHEM,
School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster
Road, Edinburgh EH9 3FJ, U.K.
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12
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Todd ZR, Szostak JW, Sasselov DD. Shielding from UV Photodamage: Implications for Surficial Origins of Life Chemistry on the Early Earth. ACS Earth Space Chem 2021; 5:239-246. [PMID: 36317066 PMCID: PMC9616438 DOI: 10.1021/acsearthspacechem.0c00270] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
UV light has been invoked as a source of energy for driving prebiotic chemistry, but such high energy photons are also known to cause damage to biomolecules and their precursors. One potential mechanism for increasing the lifetime of UV-photounstable molecules is to invoke a protection or shielding mechanism. UV shielding could either occur by the molecule in question itself (self-shielding) or by the presence of other UV-absorbing molecules. We investigate and illustrate these two shielding mechanisms as means of increasing the lifetime of 2-aminooxazole (AO), a prebiotic precursor molecule moderately susceptible to UV photodamage, with an expected half-life of 7 h on the surface of the early Earth. AO can be protected by being present in high concentrations, such that it self-shields. AO can similarly be protected by the presence of UV-absorbing nucleosides; the degree of protection depends on the concentration and identity of the nucleoside. The purine nucleosides (A, G, and I) confer more protection than the pyrimidines (C and U). We find that 0.1 mM purine ribonucleosides affords AO about the same protection as 1 mM AO self-shielding, corresponding to a lifetime enhancement of 2-3×. This suggests that only a modest yield of nucleosides can potentially allow for protection of UV photounstable molecules, and therefore this could be a plausible mechanism for protecting sensitive molecules while prebiotic synthesis is occurring simultaneously. Our findings suggest that both synthetic and degradative reactions can proceed at the same time, given various degrees of shielding.
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Affiliation(s)
- Zoe R. Todd
- Center
for Astrophysics Harvard and Smithsonian, 60 Garden Street, Cambridge, Massachusetts 02138, United States
- Howard
Hughes Medical Institute, Department of Molecular Biology and Center
for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
| | - Jack W. Szostak
- Howard
Hughes Medical Institute, Department of Molecular Biology and Center
for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
| | - Dimitar D. Sasselov
- Center
for Astrophysics Harvard and Smithsonian, 60 Garden Street, Cambridge, Massachusetts 02138, United States
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13
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Abstract
Delivery of water and organics by asteroid and comet impacts may have influenced prebiotic chemistry on the early Earth. Some recent prebiotic chemistry experiments emphasize hydrogen cyanide (HCN) as a feedstock molecule for the formation of sugars, ribonucleotides, amino acids, and lipid precursors. Here, we assess how much HCN originally contained in a comet would survive impact, using parametric temperature and pressure profiles together with a time-dependent chemistry model. We find that HCN survival mainly depends on whether the impact is hot enough to thermally decompose H2O into reactive radicals, and HCN is therefore rather insensitive to the details of the chemistry. In the most favorable impacts (low impact angle, low velocity, small radius), this temperature threshold is not reached, and intact delivery of HCN is possible. We estimate the global delivery of HCN during a period of Early and Late Heavy Bombardment of the early Earth, as well as local HCN concentrations achieved by individual impacts. In the latter case, comet impacts can provide prebiotically interesting HCN levels for thousands to millions of years, depending on properties of the impactor and of the local environment.
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Affiliation(s)
- Zoe R Todd
- Department of Astronomy, Center for Astrophysics, Harvard and Smithsonian, Cambridge, Massachusetts, USA
| | - Karin I Öberg
- Department of Astronomy, Center for Astrophysics, Harvard and Smithsonian, Cambridge, Massachusetts, USA
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14
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Todd ZR, Fahrenbach AC, Ranjan S, Magnani CJ, Szostak JW, Sasselov DD. Ultraviolet-Driven Deamination of Cytidine Ribonucleotides Under Planetary Conditions. Astrobiology 2020; 20:878-888. [PMID: 32267736 PMCID: PMC9634989 DOI: 10.1089/ast.2019.2182] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
A previously proposed synthesis of pyrimidine ribonucleotides makes use of ultraviolet (UV) light to convert β-d-ribocytidine-2',3'-cyclic phosphate to β-d-ribouridine-2',3'-cyclic phosphate, while simultaneously selectively degrading synthetic byproducts. Past studies of the photochemical reactions of pyrimidines have employed mercury arc lamps, characterized by narrowband emission centered at 254 nm, which is not representative of the UV environment of the early Earth. To further assess this process under more realistic circumstances, we investigated the wavelength dependence of the UV-driven conversion of β-d-ribocytidine-2',3'-cyclic phosphate to β-d-ribouridine-2',3'-cyclic phosphate. We used constraints provided by planetary environments to assess the implications for pyrimidine nucleotides on the early Earth. We found that the wavelengths of light (255-285 nm) that most efficiently drive the deamination of β-d-ribocytidine-2',3'-cyclic phosphate to β-d-ribouridine-2',3'-cyclic phosphate are accessible on planetary surfaces such as those of the Hadean-Archaean Earth for CO2-N2-dominated atmospheres. However, continued irradiation could eventually lead to low levels of ribocytidine in a low-temperature, highly irradiated environment, if production rates are slow.
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Affiliation(s)
- Zoe R. Todd
- Department of Astronomy, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts
- Howard Hughes Medical Institute, Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts
- Address correspondence to: Zoe R. Todd, Department of Astronomy, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street Mail-Stop 10, Cambridge, MA 02138
| | | | - Sukrit Ranjan
- SCOL Postdoctoral Fellow, Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Christopher J. Magnani
- Department of Astronomy, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts
- Howard Hughes Medical Institute, Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts
| | - Jack W. Szostak
- Howard Hughes Medical Institute, Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts
| | - Dimitar D. Sasselov
- Department of Astronomy, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts
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15
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Todd ZR, Szabla R, Szostak JW, Sasselov DD. UV photostability of three 2-aminoazoles with key roles in prebiotic chemistry on the early earth. Chem Commun (Camb) 2019; 55:10388-10391. [PMID: 31380533 DOI: 10.1039/c9cc05265h] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Three related molecules in the 2-aminoazole family are potentially important for prebiotic chemistry: 2-aminooxazole, 2-aminoimidazole, and 2-aminothiazole, which can provide critical functions as an intermediate in nucleotide synthesis, a nucleotide activating agent, and a selective agent, respectively. Here, we examine the wavelength-dependent photodegradation of these three molecules under mid-range UV light (210-290 nm). We then assess the implications of the observed degradation rates for the proposed prebiotic roles of these compounds. We find that all three 2-aminoazoles degrade under UV light, with half lives ranging from ≈7-100 hours under a solar-like spectrum. 2-Aminooxazole is the least photostable, while 2-aminoimidazole is the most photostable. The relative photostabilities are consistent with the order in which these molecules would be used prebiotically: AO is used first to build nucleotides and AI is used last to activate them.
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Affiliation(s)
- Zoe R Todd
- Department of Astronomy, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA.
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16
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Ranjan S, Todd ZR, Sutherland JD, Sasselov DD. Sulfidic Anion Concentrations on Early Earth for Surficial Origins-of-Life Chemistry. Astrobiology 2018; 18:1023-1040. [PMID: 29627997 PMCID: PMC6225604 DOI: 10.1089/ast.2017.1770] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 01/19/2018] [Indexed: 05/16/2023]
Abstract
A key challenge in origin-of-life studies is understanding the environmental conditions on early Earth under which abiogenesis occurred. While some constraints do exist (e.g., zircon evidence for surface liquid water), relatively few constraints exist on the abundances of trace chemical species, which are relevant to assessing the plausibility and guiding the development of postulated prebiotic chemical pathways which depend on these species. In this work, we combine literature photochemistry models with simple equilibrium chemistry calculations to place constraints on the plausible range of concentrations of sulfidic anions (HS-, HSO3-, SO32-) available in surficial aquatic reservoirs on early Earth due to outgassing of SO2 and H2S and their dissolution into small shallow surface water reservoirs like lakes. We find that this mechanism could have supplied prebiotically relevant levels of SO2-derived anions, but not H2S-derived anions. Radiative transfer modeling suggests UV light would have remained abundant on the planet surface for all but the largest volcanic explosions. We apply our results to the case study of the proposed prebiotic reaction network of Patel et al. ( 2015 ) and discuss the implications for improving its prebiotic plausibility. In general, epochs of moderately high volcanism could have been especially conducive to cyanosulfidic prebiotic chemistry. Our work can be similarly applied to assess and improve the prebiotic plausibility of other postulated surficial prebiotic chemistries that are sensitive to sulfidic anions, and our methods adapted to study other atmospherically derived trace species.
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Affiliation(s)
- Sukrit Ranjan
- Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA
- MIT Department of Earth, Atmospheric, and Planetary Sciences, Cambridge, Massachusetts, USA
| | - Zoe R. Todd
- Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA
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17
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Xu J, Ritson DJ, Ranjan S, Todd ZR, Sasselov DD, Sutherland JD. Photochemical reductive homologation of hydrogen cyanide using sulfite and ferrocyanide. Chem Commun (Camb) 2018; 54:5566-5569. [PMID: 29761807 PMCID: PMC5972737 DOI: 10.1039/c8cc01499j] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Photoredox cycling during UV irradiation of ferrocyanide ([FeII(CN)6]4-) in the presence of stoichiometric sulfite (SO32-) is shown to be an extremely effective way to drive the reductive homologation of hydrogen cyanide (HCN) to simple sugars and precursors of hydroxy acids and amino acids.
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Affiliation(s)
- Jianfeng Xu
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK.
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18
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Todd ZR, Fahrenbach AC, Magnani CJ, Ranjan S, Björkbom A, Szostak JW, Sasselov DD. Solvated-electron production using cyanocuprates is compatible with the UV-environment on a Hadean–Archaean Earth. Chem Commun (Camb) 2018; 54:1121-1124. [PMID: 29334083 PMCID: PMC9631354 DOI: 10.1039/c7cc07748c] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
UV-driven photoredox processing of cyanocuprates can generate simple sugars necessary for prebiotic synthesis. We investigate the wavelength dependence of this process from 215 to 295 nm and generally observe faster rates at shorter wavelengths. The most efficient wavelengths are accessible to a range of potential prebiotic atmospheres, supporting the potential role of cyanocuprate photochemistry in prebiotic synthesis on the early Earth. Simple sugars necessary for the synthesis of prebiotic molecules can be generated from UV-driven cyanocuprate photoprocessing under conditions consistent with those expected on the surface of the early Earth.![]()
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Affiliation(s)
- Zoe R. Todd
- Department of Astronomy
- Harvard-Smithsonian Center for Astrophysics
- 60 Garden Street
- Cambridge
- USA
| | - Albert C. Fahrenbach
- Howard Hughes Medical Institute
- Department of Molecular Biology and Center for Computational and Integrative Biology
- Massachusetts General Hospital
- 185 Cambridge Street
- Boston
| | - Christopher J. Magnani
- Department of Astronomy
- Harvard-Smithsonian Center for Astrophysics
- 60 Garden Street
- Cambridge
- USA
| | - Sukrit Ranjan
- Department of Astronomy
- Harvard-Smithsonian Center for Astrophysics
- 60 Garden Street
- Cambridge
- USA
| | - Anders Björkbom
- Howard Hughes Medical Institute
- Department of Molecular Biology and Center for Computational and Integrative Biology
- Massachusetts General Hospital
- 185 Cambridge Street
- Boston
| | - Jack W. Szostak
- Howard Hughes Medical Institute
- Department of Molecular Biology and Center for Computational and Integrative Biology
- Massachusetts General Hospital
- 185 Cambridge Street
- Boston
| | - Dimitar D. Sasselov
- Department of Astronomy
- Harvard-Smithsonian Center for Astrophysics
- 60 Garden Street
- Cambridge
- USA
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19
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Abstract
Abstract Methyl thioacetate, or activated acetic acid, has been proposed to be central to the origin of life and an important energy currency molecule in early cellular evolution. We have investigated the hydrolysis of methyl thioacetate under various conditions. Its uncatalyzed rate of hydrolysis is about 3 orders of magnitude faster (K=0.00663 s(-1); 100°C, pH 7.5, concentration=0.33 mM) than published rates for its catalyzed production, making it unlikely to accumulate under prebiotic conditions. However, our experiments showed that methyl thioacetate was protected from hydrolysis when inside its own hydrophobic droplets. Further, we found that methyl thioacetate protection from hydrolysis was also possible in droplets of hexane and in the membranes of nonanoic acid vesicles. Thus, the hydrophobic regions of prebiotic vesicles and early cell membranes could have offered a refuge for this energetic molecule, increasing its lifetime in close proximity to the reactions for which it would be needed. This model of early energy storage evokes an additional critical function for the earliest cell membranes.
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Affiliation(s)
- Zoe R Todd
- Department of Geosciences, Pennsylvania State University , University Park, Pennsylvania
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