Trans-acting siRNA
Brett Johnson
BMS265
Trans-acting siRNA is just like
“normal” siRNA
Trans-acting siRNA is just like
“normal” siRNA
…except for when its not.
Discovery
Biogenesis
ta-siRNAs come from TAS genes
Mechanism of Action
Trans-acting siRNAs act in trans!
Cellular Functions
• All ta-siRNAs from a TAS gene tend to have
similar targets.
• Four TAS families in Arabidopsis:
– TAS1 regulates at least 5 different targets of
unknown function
– TAS2 targets 2 Pentatricopeptide Repeat (PPR)
proteins of disputed function
– TAS3 targets three Auxin Response Factor (ARF)
genes (tasiR-ARF)
– TAS4 targets MYB transcripts (cell cycle,
metabolism)
Evolution and Conservation
• TAS1 and TAS2 ta-siRNAs are unique
to Arabidopsis
• TAS3 is conserved in rice, Arabidopsis
and maize (monocot vs. dicot lineages)
• miR390 directed biogenesis of tasiRNAs is conserved in moss (400
million years)
Potential as a Tool
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Replaced the ta-siRNAs in TAS1c and silenced
FAD2 activity to levels comparable to a null mutant
There’s More!
There’s More!
Read the wiki.