DIMACS Seminar on Math and CS in Biology


RNA Editing: Comparative and In Vitro Approaches to Molecular Evolution


Laura F. Landweber
Departments of Ecology and Evolutionary Biologyo
Princeton University


Department of Computer Science, Room 402
Princeton University


1:00 PM
Tuesday, October 24, 1995


RNA editing is the post-transcriptional addition and occasional deletion of uridines that occurs in the mitochondria of trypanosomes. This remarkable process adds hundreds of uridines to individual mitochondrial transcripts and creates over 90% of the amino acid codons in many mitochondrial genes. The other bases, adenine, cytidine and guanine, are completely conserved between the DNA and the RNA. Our phylogenetic analysis of trypanosomatid protozoa revealed that massive RNA editing is a primitive character which has been lost in recent lineages. One hypothesis is that RNA editing is a "molecular fossil" which preserved the ancestral state of the gene. The first mitochondrial genome may have been assembled from pieces, through processes such as splicing and editing. RNA editing could have contributed to the early construction and maintenance of many protein coding genes, and it may have even been an important force in the transition from an RNA world to the protein world of today.

I will also describe one example of the use of in vitro selection to isolate RNA molecules present in as few as one in 10^15 copies, which have novel catalytic properties. The steps involve an iterative procedure of selection (usually on an affinity column or by a functional assay) and PCR amplification of the rare sequences. The ability to isolate new ribozymes (RNA catalysts) from a large pool of random sequences has fueled an excitement about the possibility of uncovering early pathways of RNA evolution and exploring the vast catalytic repertoire of RNA.


Future Talks:

11/7: Mona Singh, Princeton, CompSci, computational learning and protein structure.

11/14: Jeanette Schmidt, Polytechnic, CompSci, approximate repetitions in sequences

11/28: Fred Hughson, Princeton, Chemistry, on protein structure.

12/5: Doug Deutschman, Cornell, Ecology, max likelihood models of forest ecology.

12/12: Alejandro Schaffer, NIH, multiple sequence alignment/diabetes diagnosis

Next semester:

Tandy Warnow, UPenn, CompSci, parsimony approaches to phylogeny reconstruction.

Lee Silver, Princeton, MolBiol, the genetics of addition.

Martin Weigert, Princeton, MolBiol, phylogenetic analysis in immunology.

Document last modified on October 17, 1995