RNP world
The RNP world is a hypothesized intermediate period in the origin of life characterized by the existence of ribonucleoproteins.[1] The period followed the hypothesized RNA world and ended with the formation of DNA and contemporary proteins.[2] In the RNP world, RNA molecules began to synthesize peptides. These would eventually become proteins which have since assumed most of the diverse functions RNA performed previously. This transition paved the way for DNA to replace RNA as the primary store of genetic information, leading to life as we know it.[3]
Principle of concept
Thomas Cech, in 2009, proposed the existence of the RNP world after his observation of apparent differences in the composition of catalysts in the two most fundamental processes that maintain and express genetic systems. For DNA, the maintenance, replication, and transcription processes are accomplished purely by protein polymerases. However, the mRNA processes of gene expression via splicing and protein synthesis are catalyzed by RNP complexes (the spliceosome and ribosome).
This difference between protein and ribonucleoprotein catalysts can be explained by extending the RNA world theory. The older RNA molecules were originally self-catalyzed through ribozymes, which evolved the assistance of proteins to form RNP. Thereafter, the newer DNA molecule used only the more efficient protein processes from the start. Thus, our current DNA world could have resulted from the gradual replacement of RNA catalysis machines with proteins. In this view, ribonucleoproteins and nucleotide-based cofactors are remnants of an intermediary era, the RNP world.[3]
See also
[edit]References
[edit]- ^ Cech, Thomas R. (July 2012). "The RNA Worlds in Context". Cold Spring Harbor Perspectives in Biology. 4 (7): a006742. doi:10.1101/cshperspect.a006742. ISSN 1943-0264. PMC 3385955. PMID 21441585.
- ^ Schimmel, Paul (March 2011). "The RNP bridge between two worlds". Nature Reviews Molecular Cell Biology. 12 (3): 135. doi:10.1038/nrm3061. ISSN 1471-0080. PMID 21285979. S2CID 21589855.
- ^ a b Cech, Thomas R. (2009-02-20). "Crawling Out of the RNA World". Cell. 136 (4): 599–602. doi:10.1016/j.cell.2009.02.002. ISSN 0092-8674. PMID 19239881. S2CID 13933577.