Nucleotide triphosphates, and in particular adenosine triphosphate (ATP), are small molecules that store biological energy through high energy bonds. Found in all forms of life, ATP is often referred to as the "molecular unit of currency of intracellular energy transfer ». As such, nearly all fondamental biological processes requiring energy also need ATP. IOW, life as we know it would not be possible without ATP. On the other hand, no ATP within the cell would exist without the complex molecular machines that synthesize it, knowing that these machines could not be produced without ATP! Hence the question: how ATP first comes to be?
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Oh no, not Bergman again!
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Adenosine > adenosine monophosphate > adenosine diphosphate > adenosine triphosphate
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And before phosphate, thioesters.
Goldford JE, Hartman H, Smith TF, Segrè D. Remnants of an Ancient Metabolism without Phosphate. Cell. 2017 Mar 9;168(6):1126-1134.e9. DOI: 10.1016/j.cell.2017.02.001
Abstract
Phosphate is essential for all living systems, serving as a building block of genetic and metabolic machinery. However, it is unclear how phosphate could have assumed these central roles on primordial Earth, given its poor geochemical accessibility. We used systems biology approaches to explore the alternative hypothesis that a protometabolism could have emerged prior to the incorporation of phosphate. Surprisingly, we identified a cryptic phosphate-independent core metabolism producible from simple prebiotic compounds. This network is predicted to support the biosynthesis of a broad category of key biomolecules. Its enrichment for enzymes utilizing iron-sulfur clusters, and the fact that thermodynamic bottlenecks are more readily overcome by thioester rather than phosphate couplings, suggest that this network may constitute a “metabolic fossil” of an early phosphate-free nonenzymatic biochemistry. Our results corroborate and expand previous proposals that a putative thioester-based metabolism could have predated the incorporation of phosphate and an RNA-based genetic system
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And perhaps we will see another ride around the block on the Krebs cycle.
(Named In honor of Maynard G. Krebs, the discover of the mechanisms of mitochondrial ATP production and probably the most hip of all circa 1960 biochemists.)
Seriously, though, the origin of ATP is a great topic worth revisiting every now and then. It’s a good question and a fascinating subject, @Giltil.
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