A test of fusion protein stability in the plant Arabidopsis thaliana reveals degradation signals from ACC synthase and from the plant N-end rule pathway

We tested three different protein domains for their ability to confer a short half life onto the otherwise stable test protein dihydrofolate reductase (DHFR) in the plant Arabidopsis thaliana. E-DHFR, a protein with Glu as the first residue, is metabolically unstable in Arabidopsis, indicating that Glu is a destabilizing residue of the plant N-end rule pathway. In contrast, the degradation signal deg1 from Saccharomyces cerevisiae transcription factor Matalpha2p is not recognized when present at the amino-terminus of DHFR. Finally, we show that the amino-terminal 93 amino acids of the plant protein 1-aminocyclopropane-1-carboxylic acid synthase contain a degradation signal that is also active in yeast.