Plant-Specific Domains and Fragmented Sequences Imply Non-Canonical Functions in Plant Aminoacyl-tRNA Synthetases.

Aminoacyl-tRNA synthetases (aaRSs) play essential roles in protein translation. In addition, numerous aaRSs (mostly in vertebrates) have also been discovered to possess a range of non-canonical functions. Very few studies have been conducted to elucidate or characterize non-canonical functions of plant aaRSs.

Allylic hydroxylation of triterpenoids by a plant cytochrome P450 triggers key chemical transformations that produce a variety of bitter compounds.

Cucurbitacins are highly oxygenated triterpenoids characteristic of plants in the family Cucurbitaceae and responsible for the bitter taste of these plants. Fruits of bitter melon () contain various cucurbitacins possessing an unusual ether bridge between C5 and C19, not observed in other Cucurbitaceae members. Using a combination of next-generation sequencing and RNA-Seq analysis and gene-to-gene co-expression analysis with the ConfeitoGUIplus software, we identified three P450 genes, , , and , expected to be involved in cucurbitacin biosynthesis.