Arabidopsis G1 cell cycle proteins undergo proteasome-dependent degradation during sucrose starvation

Although sucrose availability is crucial for commitment to plant cell division during G1 phase, it has remained uncertain how protein levels of core cell cycle genes are regulated. We found that Arabidopsis RETINOBLASTOMA-RELATED PROTEIN1 (AtRBR1) and three E2F proteins were degraded under limited sucrose conditions, while protein abundance increased in response to treatment with the proteasome inhibitor MG132. We conclude that Arabidopsis key cell cycle proteins are degraded in a proteasome-dependent manner during sucrose starvation in Arabidopsis suspension MM2d cells.

► A rapid decrease of AtRBR1 and E2Fs was observed after sucrose starvation.
► The protein levels remained similar levels in the presence of the proteasome inhibitor MG132.
► Sustained protein levels of AtRBR1 and E2Fs after MG132 treatment are clearly not due to an increase in mRNA levels.
► AtRBR1 and E2Fs are regulated by proteasome-dependent degradation during sucrose starvation.