[Seminar] "On the continuity between ancient geochemistry and modern biochemistry" by Dr. Liam Longo

Date

Monday, August 22, 2022 - 10:00 to 11:00

Location

C700, Lab3

Description

Speaker: Dr. Liam Longo, ELSI, Blue Marble Space Institute of Science, Tokyo Institute of Technology

Title: On the continuity between ancient geochemistry and modern biochemistry

Abstract:

Is there a plausible path from geochemical precursors to the majority of metabolites in the biosphere? Or, does the prevalence of "autocatalytic bottlenecks” in metabolism and the high extinction rates throughout Earth's history result in an apparant discontinuity? In this talk, I will describe the construction of a feasible path from simple geochemical precursors (e.g., phosphate, sulfide, ammonia, simple carboxylic acids and metals) to contemporary biochemistry. Our model includes both primitive coenzyme dependencies and thermodynamic constraints.We find that purine synthesis constitutes the primary bottleneck for metabolic expansion, resulting in a discontinuous transition. However, by proposing alternative phosphoryl coupling reactions within the purine biosynthesis pathway — amounting to just 10 additional reactions — we can restore metabolic continuity. The resulting trajectory is characterized by distinct phases of metabolic evolution, each associated with a period of rapid innovation (‘puncta'). Reactions recruited early in the metabolic expansion are preferentially associated with metal-dependent enzymes and structurally symmetric / repetitive protein folds, in keeping with models molecular evolution. The production of quinones occurs towards the end of the metabolic expansion and permits oxygenic photosynthesis, enabling the production of O2 and leading to a >30% increase in biomolecules. Take together, these results reveal a feasible trajectory from simple geochemical precursors to the majority of contemporary biochemistry.

 

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