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Biology Articles » Evolutionary Biology » Origin of Life » Modelling evolution on design-by-contract predicts an origin of Life through an abiotic double-stranded RNA world

Abstract
- Modelling evolution on design-by-contract predicts an origin of Life through an abiotic double-stranded RNA world

Hypothesis

Modelling evolution on design-by-contract predicts an origin of Life through an abiotic double-stranded RNA world

Albert DG de Roos

Syncyte BioIntelligence, PO Box 600, 1000 AP Amsterdam, The Netherlands

Background

It is generally believed that life first evolved from single-stranded RNA (ssRNA) that both stored genetic information and catalyzed the reactions required for self-replication.

Presentation of the hypothesis

By modeling early genome evolution on the engineering paradigm design-by-contract, an alternative scenario is presented in which life started with the appearance of double-stranded RNA (dsRNA) as an informational storage molecule while catalytic single-stranded RNA was derived from this dsRNA template later in evolution.

Testing the hypothesis

It was investigated whether this scenario could be implemented mechanistically by starting with abiotic processes. Double-stranded RNA could be formed abiotically by hybridization of oligoribonucleotides that are subsequently non-enzymatically ligated into a double-stranded chain. Thermal cycling driven by the diurnal temperature cycles could then replicate this dsRNA when strands of dsRNA separate and later rehybridize and ligate to reform dsRNA. A temperature-dependent partial replication of specific regions of dsRNA could produce the first template-based generation of catalytic ssRNA, similar to the developmental gene transcription process. Replacement of these abiotic processes by enzymatic processes would guarantee functional continuity. Further transition from a dsRNA to a dsDNA world could be based on minor mutations in template and substrate recognition sites of an RNA polymerase and would leave all existing processes intact.

Implications of the hypothesis

Modeling evolution on a design pattern, the 'dsRNA first' hypothesis can provide an alternative mechanistic evolutionary scenario for the origin of our genome that preserves functional continuity.

Reviewers

This article was reviewed by Anthony Poole, Eugene Koonin and Eugene Shakhnovich

Biology Direct 2007, 2:12. This is an Open Access article distributed under the terms of the Creative Commons Attribution License.


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