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.
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
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