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ATP Synthase is ubiquitous throughout life on earth and so most probably evolved within the last universal common ancestor (LUCA) before that lineage diversified into the various kingdoms of life.

It is suggested that the functional domains comprising the ATP Synthase complex were cobbled together from pre-existing sub-units, each with with a related activity (e.g. the union of a proton motor with a DNA Helicase with ATPase activity), which seems reasonable, although a bit vague in the details.

The fact that a primitive ATP Synthase arose in the first place suggests that ATP already had a central role in cellular metabolism and so begs the question, what preceded ATP Synthase in the role of generating ATP in the LUCA cell?

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  • $\begingroup$ ATP Synthase is NOT ubiquitous throughout life on earth. It is lacking from most anaerobic organisms. $\endgroup$ – David Jan 19 at 19:27
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There are metabolic processes in which ATP is synthesised without the involvement of ATP synthase. The best examples are, in fact, two steps in the glycolytic pathway, catalysed by phosphoglycerate kinase and pyruvate kinase. This is why, in the absence of any aerobic metabolism, many organisms (like yeast for example) can grow quite happily, producing two molecules of ATP for each molecule of glucose that is metabolised.

Presumably this process is what enabled ATP to gain its central role in energy metabolism without any need for an ATP synthase.

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We don't know much about early evolution of life. However it is believed that energetic molecules (analogous to ATP) may have evolved before everything else. These energetic molecules may have driven different metabolic reactions (which need not be catalyzed by big protein enzymes). Also, it is believed that natural chemical gradients would have been used by primitive life-forms to obtain the energy.

You can have a look at this article. I am pasting the list of references/recommended reading mention in this article so that you may search for them individually even if this article is not accessible any longer.


- Allen, J. F. The function of genomes in bioenergetic organelles. Philosophical Transactions of the Royal Society of London B: Biological Sciences 358, 19–37 (2003)

- Efremov, R. G., Baradaran, R. & Sazanov, L. The architecture of respiratory complex I. Nature 465, 441–445 (2010) doi:10.1038/nature09066

- Lane, N., Allen, J. F. & Martin, W. How did LUCA make a living? Chemiosmosis in the origin of life. Bioessays 32, 271–280 (2010) doi:10.1002/bies.200900131

- Lane, N. & Martin, W. The energetics of genome complexity. Nature 467, 929-934 (2010)

- Martin, W. & Russell, M. On the origin of biochemistry at an alkaline hydrothermal vent. Philosophical Transactions of the Royal Society of London B: Biological Sciences 362, 1887–1925 (2007)

- Mitchell, P. Coupling of phosphorylation to electron and hydrogen transfer by a chemi-osmotic type of mechanism. Nature 191, 144–148 (1961) doi:10.1038/191144a0

- Orgel, L. Are you serious, Dr Mitchell? Nature 402, 17 (1999) doi:10.1038/46903

- Russell, M. J. First life. American Scientist 94, 32–39 (2006)

- Silverstein, T. The mitochondrial phosphate-to-oxygen ratio is not an integer. Biochemistry and Molecular Biology Education 33, 416–417 (2005)

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    $\begingroup$ Is this really a chicken–egg question? It just seems to be asking whether a simpler method of ATP generation preceeded the ATP synthase and if so what. Isn't this actually acknowledging the solution to the real chicken/egg problems with ATP, such the need for ATP in the synthesis of the adenine ring of ATP? Your list of references is very useful, but can I suggest you provide more context by naming the "energetic molecules" you mention. $\endgroup$ – David Jan 20 at 14:11
  • $\begingroup$ @David point taken. The energetic molecules that I mention haven't really been identified. It is just hypothetical. This is probably mentioned in one of the references. Nonetheless, I'll try to look up and provide some more context asap. $\endgroup$ – WYSIWYG Jan 21 at 8:49

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