1. Canavanine is found in seeds (alfalfa)
• Functions as an analogue
to arginine
Thelongestlife.com

2. Canavanine enters
yeast via an arginine
permease (CAN1)
http://2011.igem.org/Team:SJTU-BioX-
Shanghai/Project/Subproject1-1
• Once in the cell,
canavanine
becomes
incorporated into
proteins instead
of arginine
http://www.biologie.uni-freiburg.de/data/bio3/igloi/Accuracy.htm

3. Arginyl-tRNA synthetase attaches
canavanine to tRNA
• Species (tobacco
budworm - Heliothis
virescens) that eat
canavanine seeds
have a highly
discriminatory
synthetase
• Non-discriminatory
synthetase in yeast Wikipedia

4. UV radiation will randomly induce
mutations in the yeast DNA
http://blogs.scientificamerican.com/observatio
ns/2010/07/25/subatomic-sunscreen-how-
light-particles-can-repair-uv-damaged-dna/

5. If the UV radiation mutates CAN1,
canavanine no longer enters the cell,
Yeastgenome.org
and the cell survives

6. Chain of events…
Control (no UV radiation) UV Radiation
Canavanine enters cell via CAN1 Canavanine enters cell via CAN1
Canavanine attached to tRNA Canavanine attached to tRNA
Canavanine incorporated into protein Canavanine incorporated into protein
Protein misfolds Protein folds correctly
Cell dies Cell survives

7. The UV radiation mutation rate will be greater
compared to the spontaneous mutation rate
Control
Canavanine Plates
UV Radiation
Lidza Kalifa, Elaine A. Sia, Analysis of Rev1p and Pol ζ
in mitochondrial mutagenesis suggests an alternative
pathway of damage tolerance, DNA Repair, Volume 6,
Issue 12, 1 December 2007, Pages 1732-1739