Trans-acting siRNA Brett Johnson BMS265
Trans-acting siRNA is just like “normal” siRNA …except for when its not.
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 ta-siRNAs is conserved in moss (400 million years)
Potential as a Tool Replaced the ta-siRNAs in TAS1c and silenced FAD2 activity to levels comparable to a null mutant
There’s More! Read the wiki.