Amazing news about the origin of life.

 Minerals near deep-sea hydrothermal ventspromote the formation of energy-rich organicmolecules that life needed to get its start.Was this life's first meal?By Robert F. ServiceMar. 2, 2020 , 12:30 PMStudies of the origin of life are replete withparadoxes.Take this doozy: Every known organism onEarth uses a suite of proteins-and the DNAthat helps build it-to construct the buildingblocks of our cells.But those very building blocks are also neededto make DNA and proteins.The solution to this chicken-and-egg conundrummay lie at the site of hydrothermal vents, fissuresin the sea floor that spew hot water and a wealthof other chemicals, researchers report today.Scientists say they have found that a trio of metalcompounds abundant around the vents can causehydrogen gas and carbon dioxide (CO2) to reactto form a collection of energy-rich organiccompounds critical to cell growth.And the high temperatures and pressures aroundthe vents themselves may have jump-started lifeon Earth, the team argues.The new work is "thrilling," says Thomas Carell,an origin of life chemist at Ludwig MaximilianUniversity of Munich who was not affiliated withthe new project.The organic molecules the study generatedinclude formate, acetate, and pyruvate, whichCarell calls "the most fundamental moleculesof energy metabolism," the process of convertingnutrients into cell growth.The new results support a long-held idea aboutthe origin of life known as "metabolism firsthypothesis." It posits that geochemical processes on early Earth created a stew of simple energy-richcompounds that drove the synthesis of complexmolecules, which eventually provided thematerials for Darwinian evolution and life. SIGN UP FOR OUR DAILY NEWSLETTERGet more great content like this delivered right to you!A clue to this primordial metabolism came in 2016.Researchers led by William Martin, an evolutionarybiologist at Heinrich Heine University of Dusseldorf,scanned the genomes of thousands of bacteria andarchaea, identifying 355 proteins encoded by sharedgenes that likely belonged to a microbial Eve, thelast universal common ancestor of all life.Those proteins suggest this primordial microbethrived in scalding temperatures and ate hydrogengas, using its electrons to convert inorganic CO2 dissolved in the ocean into energy-rich organiccompounds.That supports the notion that the microbes livednear hydrothermal vents, where those conditionswould have been present.That idea is bolstered by the fact that modernorganisms still combine hydrogen and CO2 tomake organic molecules in a process knownas the acetyl-coenzyme A (acetyl-CoA) pathway.This process feeds essential organic moleculesinto biochemical processes that drive theproduction of proteins, carbohydrates, and lipids,which is at the heart of energy metabolism in cells.The problem, however, is that modern organismsrun the acetyl-CoA pathway using 11 enzymesmade up of a combined 15,000 amino acids, allfinely positioned to carry out their work.And without the right protein machinery or catalyst,if you put hydrogen and CO2 together, Martin says,"Nothing will happen."So how could organisms have spontaneouslydeveloped their prowess to run the acetyl-CoApathway? Two years ago, researchers led by JosephMoran, a chemist at the University of Strasbourg,suggested at least a partial answer.They reported that pure metals, including iron,nickel, and cobalt, could catalyze the reaction ofwater (water molecules contain hydrogen) andCO2 to form acetate and pyruvate, key membersof the acetyl-CoA pathway.That finding suggests the earliest life could havesimply fed on these organic compounds to geta toehold, and over time evolved a suite of proteinsto make the reactions even more efficient.Still, Martin notes, converting water and CO2 intoneeded organics isn't how microbial Eve's mostclosely related modern brethren do it.Rather, these organisms start with hydrogen gasand CO2. "We wanted to see if we could get thispathway to work without enzymes," Martin says.He and his colleagues knew hydrothermal ventscontinually spew out hydrogen gas, driven byreactions between water and metals deep belowEarth's crust.And researchers previously determined that CO2 in early Earth's oceans was about 1000 timesmore abundant than it is today.So, Martin wondered whether metal-rich mineralscommon around hydrothermal vents could causehydrogen to react with CO2.To find out, Martin's and Moran's teams joinedforces to investigate three iron-rich minerals foundnear vents: greigite, magnetite, and awaruite.They added these to a water solution and bubbledin hydrogen and CO2 at 100°C and 25 bars ofpressure, conditions common around deep-seavents.All three minerals catalyzed a reaction of hydrogenand CO2 to form a mix of organics including formate,acetate, and pyruvate, the group reports todayin Nature Ecology & Evolution."What we have here is a sustained source ofchemical energy, and it generates these energy-rich molecules used in metabolism," Martin says.So, was this mix of organics life's first meal? It'sa fair bet, says Steven Benner, a chemist at theFoundation for Applied Molecular Evolution.For evolution to begin, life would have needed botha food source and some form of protogeneticmolecule to transmit information from one organismto its progeny.How they came together is still unclear.However, any early Darwinian system would needto feed.And, Benner says: "The process described by[Martin's and Moran's team] could certainly have been the source of some of their food."Posted in: ChemistryEarthdoi:10.1126/science.abb5418Robert F. ServiceBob is a news reporter for Science in Portland,Oregon, covering chemistry, materials science,and energy stories.