All Life on Earth uses the same Chemicals for Energy. This may explain why. : ScienceAlert | Whuff News


All life as we know it uses the most energy-carrying molecule as a form of ‘universal cell fuel’. Now, ancient chemistry can explain how this important molecule ended up being ATP (adenosine triphosphate) a new study reports.

ATP is a living molecule, which is charged by photosynthesis or cellular respiration (the way organisms break down food) and is used in every cell. Every day, we recycle our body weight in ATP.

In both of the above processes, a phosphate molecule is added to ADP (adenosine diphosphate) through a reaction called phosphorylation – caused by ATP.

Reactions that release that same phosphate (in another process called hydrolysis) provide the chemical energy our cells use for many processes, from brain signals to movement and reproduction.

How ATP rose to metabolic dominance, instead of many other factors, has been a long-standing mystery in biology and a focus of research.

“Our results show … that the emergence of ATP as the universal energy currency of the cell was not the result of a ‘frozen accident’,” but arose from a special interaction of phosphorylation molecules, explains biochemist Nick Lane from the University of London (UCL). ).

The fact that ATP is used by all living things shows that it was there from the beginning of life and before, during the prebiotic conditions that preceded all living things.

But researchers are puzzled how this can happen when ATP has a complex structure that involves six different phosphorylation reactions and a lot of energy to create it from scratch.

There is nothing special about ‘higher powers’ [phosphorus] bonds to ATP,” said chemist Silvana Pinna who was with UCL at the time, and colleagues in their paper.

But since ATP also helps build the genetic information of our cells, it could be harnessed for energy use in another way, they note.

Pinna and team suspect that other molecules must be involved initially in the complex process of phosphorylation. So they looked at another phosphorylating molecule, AcP, which is used by bacteria and archaea in their metabolism of chemicals, including phosphate and thioester – a chemical thought to be abundant at the beginning of life.

In the presence of iron ions (Fe3+), AcP can phosphorylate ADP to ATP in water. In testing the ability of other ions and minerals to make ATP able to make ATP in water, researchers were not able to repeat this with other replacement metals or phosphorylating molecules.

“It was very surprising to find that the response is very selective – to the metal ion, the phosphate donor, and the substrate – and the molecules that are still used by life,” said Pinna.

“The fact that this happens well in water under cool, life-friendly conditions is very important for the origin of life.”

This suggests that with AcP, these energy-saving reactions can occur in prebiotic conditions, before biological life exists to accumulate and promote the self-sustaining cycle of ATP production.

Moreover, the tests show that the creation of prebiotic ATP was possible in fresh water, where photochemical reactions and volcanic eruptions, for example, can provide the right combination of ingredients, the team explains.

Although this does not completely rule out its occurrence in the ocean, it does indicate that the birth of life may require a strong link to land, they note.

“Our results show that ATP was established as a global energy currency in the prebiotic, monomeric world, on the basis of unusual chemistry in water,” Pinna and colleagues wrote.

Moreover, pH gradients in hydrothermal systems can create an unbalanced ratio of ATP to ADP, which makes ATP active even in the prebiotic world of small molecules.

“Over time, with the development of the right factors, ATP can replace AcP as a ubiquitous phosphate donor, and promote the polymerization of amino acids and nucleotides to make RNA, DNA, and proteins,” explains Lane.

This research was published in PLOS Biology.



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