Phosphates as Energy Sources to Expand Metabolic Networks.

Xin-Yi Chu,Bin-Guang Ma,Jun Gao,Yi Yang,Ye-Mao Liu,Xuan Zhang,Tian Tian,Hong-Yu Zhang

doi:10.3390/life9020043

Abstract

Phosphates are essential for modern metabolisms. A recent study reported a phosphate-free metabolic network and suggested that thioesters, rather than phosphates, could alleviate thermodynamic bottlenecks of network expansion. As a result, it was considered that a phosphorus-independent metabolism could exist before the phosphate-based genetic coding system. To explore the origin of phosphorus-dependent metabolism, the present study constructs a protometabolic network that contains phosphates prebiotically available using computational systems biology approaches. It is found that some primitive phosphorylated intermediates could greatly alleviate thermodynamic bottlenecks of network expansion. Moreover, the phosphorus-dependent metabolic network exhibits several ancient features. Taken together, it is concluded that phosphates played a role as important as that of thioesters during the origin and evolution of metabolism. Both phosphorus and sulfur are speculated to be critical to the origin of life.

Highlights

IntroductionPhosphate minerals existing on the early Earth or in meteorites are thought to be the main sources of prebiotic phosphorus [1,2,3]
Phosphates are basic components of many biomolecules and essential for modern biochemical reactions, but it is still not clear how phosphates play the critical role in metabolism in the origin of life.Phosphate minerals existing on the early Earth or in meteorites are thought to be the main sources of prebiotic phosphorus [1,2,3]
They constructed a phosphorus-independent protometabolism network starting from a set of prebiotically abundant compounds excluding phosphates

Summary

Introduction

Phosphate minerals existing on the early Earth or in meteorites are thought to be the main sources of prebiotic phosphorus [1,2,3] Most of these phosphates are either insoluble in water or have low reactivity and they are considered to be problematic for primordial biological use [1]. The researchers found that sulfur compounds (i.e., pantetheine) could alleviate the thermodynamic bottlenecks of the network expansion while phosphates (i.e., pyrophosphate or acetyl-phosphate) could not Based on these findings, Goldford et al proposed that a phosphorus-independent metabolism could exist before the emergence of the phosphate-based genetic coding system. This phosphorus-independent network could not produce nucleobases or ribose, which means that this network is unlikely a possible source of RNA

Methods

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Conclusion