Cargando…

A carbonate-rich lake solution to the phosphate problem of the origin of life

Phosphate is central to the origin of life because it is a key component of nucleotides in genetic molecules, phospholipid cell membranes, and energy transfer molecules such as adenosine triphosphate. To incorporate phosphate into biomolecules, prebiotic experiments commonly use molar phosphate conc...

Descripción completa

Detalles Bibliográficos
Autores principales: Toner, Jonathan D., Catling, David C.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: National Academy of Sciences 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6969521/
https://www.ncbi.nlm.nih.gov/pubmed/31888981
http://dx.doi.org/10.1073/pnas.1916109117
_version_ 1783489342606409728
author Toner, Jonathan D.
Catling, David C.
author_facet Toner, Jonathan D.
Catling, David C.
author_sort Toner, Jonathan D.
collection PubMed
description Phosphate is central to the origin of life because it is a key component of nucleotides in genetic molecules, phospholipid cell membranes, and energy transfer molecules such as adenosine triphosphate. To incorporate phosphate into biomolecules, prebiotic experiments commonly use molar phosphate concentrations to overcome phosphate’s poor reactivity with organics in water. However, phosphate is generally limited to micromolar levels in the environment because it precipitates with calcium as low-solubility apatite minerals. This disparity between laboratory conditions and environmental constraints is an enigma known as “the phosphate problem.” Here we show that carbonate-rich lakes are a marked exception to phosphate-poor natural waters. In principle, modern carbonate-rich lakes could accumulate up to ∼0.1 molal phosphate under steady-state conditions of evaporation and stream inflow because calcium is sequestered into carbonate minerals. This prevents the loss of dissolved phosphate to apatite precipitation. Even higher phosphate concentrations (>1 molal) can form during evaporation in the absence of inflows. On the prebiotic Earth, carbonate-rich lakes were likely abundant and phosphate-rich relative to the present day because of the lack of microbial phosphate sinks and enhanced chemical weathering of phosphate minerals under relatively CO(2)-rich atmospheres. Furthermore, the prevailing CO(2) conditions would have buffered phosphate-rich brines to moderate pH (pH 6.5 to 9). The accumulation of phosphate and other prebiotic reagents at concentration and pH levels relevant to experimental prebiotic syntheses of key biomolecules is a compelling reason to consider carbonate-rich lakes as plausible settings for the origin of life.
format Online
Article
Text
id pubmed-6969521
institution National Center for Biotechnology Information
language English
publishDate 2020
publisher National Academy of Sciences
record_format MEDLINE/PubMed
spelling pubmed-69695212020-01-27 A carbonate-rich lake solution to the phosphate problem of the origin of life Toner, Jonathan D. Catling, David C. Proc Natl Acad Sci U S A Physical Sciences Phosphate is central to the origin of life because it is a key component of nucleotides in genetic molecules, phospholipid cell membranes, and energy transfer molecules such as adenosine triphosphate. To incorporate phosphate into biomolecules, prebiotic experiments commonly use molar phosphate concentrations to overcome phosphate’s poor reactivity with organics in water. However, phosphate is generally limited to micromolar levels in the environment because it precipitates with calcium as low-solubility apatite minerals. This disparity between laboratory conditions and environmental constraints is an enigma known as “the phosphate problem.” Here we show that carbonate-rich lakes are a marked exception to phosphate-poor natural waters. In principle, modern carbonate-rich lakes could accumulate up to ∼0.1 molal phosphate under steady-state conditions of evaporation and stream inflow because calcium is sequestered into carbonate minerals. This prevents the loss of dissolved phosphate to apatite precipitation. Even higher phosphate concentrations (>1 molal) can form during evaporation in the absence of inflows. On the prebiotic Earth, carbonate-rich lakes were likely abundant and phosphate-rich relative to the present day because of the lack of microbial phosphate sinks and enhanced chemical weathering of phosphate minerals under relatively CO(2)-rich atmospheres. Furthermore, the prevailing CO(2) conditions would have buffered phosphate-rich brines to moderate pH (pH 6.5 to 9). The accumulation of phosphate and other prebiotic reagents at concentration and pH levels relevant to experimental prebiotic syntheses of key biomolecules is a compelling reason to consider carbonate-rich lakes as plausible settings for the origin of life. National Academy of Sciences 2020-01-14 2019-12-30 /pmc/articles/PMC6969521/ /pubmed/31888981 http://dx.doi.org/10.1073/pnas.1916109117 Text en Copyright © 2020 the Author(s). Published by PNAS. https://creativecommons.org/licenses/by-nc-nd/4.0/ https://creativecommons.org/licenses/by-nc-nd/4.0/This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND) (https://creativecommons.org/licenses/by-nc-nd/4.0/) .
spellingShingle Physical Sciences
Toner, Jonathan D.
Catling, David C.
A carbonate-rich lake solution to the phosphate problem of the origin of life
title A carbonate-rich lake solution to the phosphate problem of the origin of life
title_full A carbonate-rich lake solution to the phosphate problem of the origin of life
title_fullStr A carbonate-rich lake solution to the phosphate problem of the origin of life
title_full_unstemmed A carbonate-rich lake solution to the phosphate problem of the origin of life
title_short A carbonate-rich lake solution to the phosphate problem of the origin of life
title_sort carbonate-rich lake solution to the phosphate problem of the origin of life
topic Physical Sciences
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6969521/
https://www.ncbi.nlm.nih.gov/pubmed/31888981
http://dx.doi.org/10.1073/pnas.1916109117
work_keys_str_mv AT tonerjonathand acarbonaterichlakesolutiontothephosphateproblemoftheoriginoflife
AT catlingdavidc acarbonaterichlakesolutiontothephosphateproblemoftheoriginoflife
AT tonerjonathand carbonaterichlakesolutiontothephosphateproblemoftheoriginoflife
AT catlingdavidc carbonaterichlakesolutiontothephosphateproblemoftheoriginoflife