Beta-Sheet Polypeptides as Prebiotic Informational Molecular Entities

From the Abiogenesis mailing list.

One of the critical steps in the development of life from nonliving chemicals was the development of a mechanism for storing information and passing it to the next "generation". 

The beta sheet is one of the very basic high-level structures that amino acid strings naturally form.  Now it seems these sheets not only can store information, they resist destruction under the environmental conditions that existed in the early Earth.

 

From: J Sullivan <wa1tej@yahoo.com>

Date: Mon, Mar 30, 2009 at 12:24 AM

 

 

Orig Life Evol Biosph. 2009 Apr;39(2):141-50. Epub 2009 Mar 20.

Self-Propagating beta-Sheet Polypeptide Structures as Prebiotic Informational Molecular Entities: The Amyloid World.

Maury CP

Department of Medicine, University of Helsinki, Kasarmikatu 11-13, FI-00130, Helsinki, Finland, peter.maury@hus.fi.

The idea is advanced that under the extreme earth conditions for ~3.9 billions years ago, protein-based beta-sheet molecular structures were the first self-propagating and information-processing biomolecules that evolved. The amyloid structure of these aggregates provided an effective protection against the harsh conditions known to decompose both polyribonucleotides and natively folded polypeptides. In the prebiotic amyloid world, both the replicative and informational functions were carried out by structurally stable beta-sheet protein aggregates in a prion-like mode involving templated self-propagation and storage of information in the beta-sheet conformation. In this amyloid (protein)-first, hybrid replication-metabolism view, the synthesis of RNA, and the evolvement of an RNA-protein world, were later, but necessary events for further biomolecular evolution to occur. I further argue that in our contemporary DNA<-->RNA-->protein world, the primordial beta-conformation-based information system is preserved in the form of a cytoplasmic epigenetic memory.