|Thu., Aug. 25||PM||Symposia/Workshops, Oral/Poster presentations|
|Fri., Aug. 26||AM||Plenary symposium|
|PM||Symposia/Workshops, Oral/Poster presentations|
|Sat., Aug. 27||AM||Symposia/Workshops|
|PM||Poster presentations, High-school students' poster presentations,|
General assembly of the society, Banquet
|Sun. Aug. 28||AM||Summer school (admission free)|
|PM||Public lectures (admission free)|
"Cabinet of curiosities at Tokyo Tech" A Special Sale of Animal Merchandise:
Thu., Aug. 25 - Sun. Aug. 28 (10:00 - 16:00 for each day)
Fri., Aug. 26 9:00-11:00
- ¢žMartin Sikora
(Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen)
- The Genomic Tag Hypothesis for the Origin of tRNA and Genomic RNA Replication in the RNA World
¢žAlan Weiner and Nancy Maizels
(Department of Biochemistry, University of Washington School of Medicine)
””Following the discovery of catalytic RNA in 1982 by Tom Cech, Sid Altman, and Norm Pace, most molecular biologists concluded without hesitation that RNA (or something like RNA) was the first "living" molecule on earth. The discovery of catalytic RNA liberated molecular biologists from asking whether DNA (an informational molecule) or protein (a catalytic molecule) came first (the famous "chicken and egg question"). Instead, RNA could be both catalytic and informational, and thus capable of both replication and evolution.
””The more we learn about molecular biology and evolution, the more plausible this deceptively simple scenario becomes; however, many difficult problems remain. Two of the most important problems are: How did RNA first arise from prebiotic chemical reactions? And if RNA was the first "living" molecule capable of replication and evolution, how did protein synthesis evolve? In recent breakthroughs, Powner et al. (1) and Becker et al. (2) may have solved the first problem by exploiting the power of what Szostak calls "systems chemistry" (3). We originally addressed the second problem in 1987 with our "Genomic Tag Hypothesis" for the origin of protein synthesis (4) and subsequently extended our model in 1999 (5).
””The basic idea of the Genomic Tag Hypothesis is that tRNA first evolved as a 3' terminal structure on linear RNA genomes that enabled the RNA replicase to copy the genomic template from the very 3' end. Thus tRNA would have evolved initially to facilitate replication in the RNA World, and only later have been adapted (or "exapted") as the central component of protein synthesis in the emerging RNP (ribonucleoprotein) World. As evidence for this hypothesis, we describe many "molecular fossils" - RNA viruses, retroplasmids, retroviruses, and modern telomerase that can be arranged in a plausible line of Darwinian "descent with modification." As corollaries, we argue that (a) some RNA viruses are survivors from the RNA World; (b) retroviruses and related pararetroviruses are survivors from a world in transition from RNA to DNA genomes; (c) the CCA-adding enzyme (also known as tRNA nucleotidyltransferase) originally functioned as an RNA telomerase in the RNA World; and (d) modern DNA telomerase activity originated as abortive initiation by a retroelement reverse transcriptase repeatedly copying the 3' end of its genomic RNA.
1. Powner, Gerland, Sutherland (2009) Synthesis of activated pyrimidine ribonucleotides in prebiotically plausible conditions. Nature 459, 239.
2. Becker, Thoma, Deutsch, Gehrke, Mayer, Zipse, Carell (2016) A high-yielding, strictly regioselective prebiotic purine nucleoside formation pathway. Science 352, 833.
3. Szostak (2009) Origins of life: Systems chemistry on early Earth. Nature 459, 171.
4. Weiner and Maizels (1987) 3' terminal tRNA-like structures tag genomic RNA molecules for replication: Implications for the origin of protein synthesis. PNAS 84, 7383
5. Maizels and Weiner (1999) The genomic tag hypothesis: What molecular fossils tell us about the evolution of tRNA. Chapter 3, in The RNA World II, Gesteland, Cech, and Atkins, eds. Cold Spring Harbor Press.
Fri., Aug. 26 11:00-12:00
- ¢žJeff Errington (video lecture) and ¢žYoshikazu Kawai
(Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Medical School, Newcastle University)