On the Origin of Sequence.

Peter Gulik

doi:10.3390/life5041629

Abstract

Three aspects which make planet Earth special, and which must be taken in consideration with respect to the emergence of peptides, are the mineralogical composition, the Moon which is in the same size class, and the triple environment consisting of ocean, atmosphere, and continent. GlyGly is a remarkable peptide because it stimulates peptide bond formation in the Salt-Induced Peptide Formation reaction. The role glycine and aspartic acid play in the active site of RNA polymerase is remarkable too. GlyGly might have been the original product of coded peptide synthesis because of its importance in stimulating the production of oligopeptides with a high aspartic acid content, which protected small RNA molecules by binding Mg2+ ions. The feedback loop, which is closed by having RNA molecules producing GlyGly, is proposed as the essential element fundamental to life. Having this system running, longer sequences could evolve, gradually solving the problem of error catastrophe. The basic structure of the standard genetic code (8 fourfold degenerate codon boxes and 8 split codon boxes) is an example of the way information concerning the emergence of life is frozen in the biological constitution of organisms: the structure of the code contains historical information.

Highlights

In this review we consider four interesting topics in succession
It is a realistic possibility that this special aspect was essential for the emergence of life. Taking these three special aspects together, one can conclude that it possibly is wishful thinking to strive to find extraterrestrial life in time and space close enough to the Solar System to be detectable. These considerations should be kept in mind when studying the role of small peptides in the emergence of life: the circumstances in which life emerged possibly were rare in the Universe
The RNA oligomers were proposed to be able to produce, in a coded way, GlyGly

Summary

Introduction

In this review we consider four interesting topics in succession. The first of these is the improbability of the origin of life. The second is the origin of the feedback loop underlying life. This is followed by error robustness, the third topic. The fourth and last topic of this review is the information frozen in the genetic code.

The Improbability of the Origin of Life

The Origin of the Feedback Loop

Error Robustness

The Information Frozen in the Genetic Code

Concluding Remarks