“RNA World” theory strongly supported
from the sing-repeatedly-"It-Was-an-RNA-World-After-All" dept.
Foresight chairman EricDrexler points out this story from Chemical & Engineering News: "The best evidence yet that, before there were proteins, there was once a world in which RNA both provided genetic information and catalyzed chemical reactions comes from a trio of papers in the current issue of Science. In a tour de force of X-ray crystallography, chemists at Yale University have located most of the atoms in the gigantic apparatus that cells use to link amino acids together into proteins. The heart of the apparatus where peptide bonds form, they find, is composed entirely of RNA." See also The RNA World book.
August 20th, 2000 at 12:31 PM
prions!
Several years ago, yeast were irradiated to destroy all DNA and RNA, and that irradiated extract was found to trasmit certain minor hereditary traits to a living yeast strain that previously lacked them. The transfer agent turned out to be prion like naked proteins! So prions might just have preceeded RNA and DNA.
August 20th, 2000 at 9:10 PM
Re:prions!
More information on the research mentioned above, on the transmission of hereditary information via proteins, can be found at this site (Howard Hughes Medical Institute).
August 20th, 2000 at 9:27 PM
Ribosome is a Ribozyme: See previous posts
The C&EN article is a secondary report on one of the items posted here on 12 August 2000; see those also.
The apparent structure seems to indicate that the active site of the ribosome comprises catalytic RNA, with no protein co-factors near enough to be considered functional parts of the peptide-bond formation apparatus. The inference is that the ribosome is an RNA-enzyme (i.e., a ribozyme).
This finding certainly does add weight to the biogenesis theories that early replicators were autocatalytic RNA. Is the ribosomal catalytic core the remnant of the first stable replicating molecules? Is everything else since then an evolutionary accretion?
August 21st, 2000 at 3:35 AM
Re:Ribosome is a Ribozyme: See previous posts
Prions 'duplicate' by themselves, but only by 'corrupting' other proteins, chicken and egg…