Linked cycles of oxidative decarboxylation of glyoxylate as protometabolic analogs of the citric acid cycle
Greg Springsteen, Jayasudhan Reddy Yerabolu, Julia Nelson, Chandler Joel Rhea & Ramanarayanan Krishnamurthy
Nature Communications 9, Article number: 91 (2018)
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Metabolic pathwaysOrganic chemistryChemical origin of lifeReaction mechanisms
Received: 23 August 2017 Accepted: 08 December 2017
Published online: 08 January 2018
Abstract
The development of metabolic approaches towards understanding the origins of life, which have focused mainly on the citric acid (TCA) cycle, have languished—primarily due to a lack of experimentally demonstrable and sustainable cycle(s) of reactions. We show here the existence of a protometabolic analog of the TCA involving two linked cycles, which convert glyoxylate into CO2 and produce aspartic acid in the presence of ammonia. The reactions proceed from either pyruvate, oxaloacetate or malonate in the presence of glyoxylate as the carbon source and hydrogen peroxide as the oxidant under neutral aqueous conditions and at mild temperatures. The reaction pathway demonstrates turnover under controlled conditions. These results indicate that simpler versions of metabolic cycles could have emerged under potential prebiotic conditions, laying the foundation for the appearance of more sophisticated metabolic pathways once control by (polymeric) catalysts became available.
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