Friday, September 08, 2006

Prions related to the emergence of early life?

Today looks to be shaping up as science day. I came across this article in the non-peer reviewed journal Medical Hypotheses (impact factor 0.920). Just what its title suggests, it is a forum for theoretical ideas.

The article suggests the possiblity that prions--proteins responsible for Mad Cow Disease and other nastiness--played an important role in the emergance of life. I am ill-qualified (MS in geology) to pass scientific judgement on the idea, but I did enjoy the article. This is from the abstract:
DNA and RNA are the modern cellular molecules related to the storage and processing of the genetic information. However, in the Earth primeval environment conditions, these two molecules are far from being the best option for this function due to their great complexity and sensibility to heat. Experiments have been showing that proteins are very stable and reliable molecules even in very extreme conditions and, under certain circumstances, could be related to the transmission of certain phenotypes that are inherited in a non-Mendelian manner.

Prions, infective proteins that are associated to several neurological diseases among mammals by replacing their dominant native state of prion protein by a misfolded one, are remarkably resistant to even the most extreme environments. Furthermore, prions are also associated to the transmission of certain fungal traits in an epigenetical model. These two characteristics support the hypothesis that prions are a possible relic of early stage peptide evolution and may represent the reminiscence of a very ancient analogical code of biological transmission of information rather than the digital one represented by modern nucleic acids.