Journal Article

Cytokinin Inhibits the Proteasome-Mediated Degradation of Carbonylated Proteins in <i>Arabidopsis</i> Leaves

Vanita Jain, Werner Kaiser and Steven C. Huber

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 49, issue 5, pages 843-852
Published in print May 2008 | ISSN: 0032-0781
Published online May 2008 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcn060
Cytokinin Inhibits the Proteasome-Mediated Degradation of Carbonylated Proteins in Arabidopsis Leaves

More Like This

Show all results sharing these subjects:

  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

GO

Show Summary Details

Preview

Under normal conditions, plants contain numerous carbonylated proteins, which are thought to be indicative of oxidative stress damage. Conditions that promote formation of reactive oxygen species (ROS) enhance protein carbonylation, and protein degradation is required to reverse the damage. However, it is not clear how the degradation of carbonylated proteins is controlled in planta. In this report, we show that detached Arabidopsis leaves rapidly and selectively degrade carbonylated proteins when kept in the dark. The loss of carbonylated proteins corresponded to a loss of soluble protein and accumulation of free amino acids. Degradation of carbonylated proteins and the loss of soluble protein was blocked by MG132 but not 3-methyladenine, suggesting that the 26S proteasome pathway rather than the autophagic pathway was involved. Consistent with this, rpn10 and rpn12 mutants, which are defective in proteasome function, had increased (rather than decreased) levels of carbonylated proteins when detached in the dark. Feeding metabolites (amino acids and sucrose) to detached leaves of wild-type Arabidopsis in the dark had little or no effect on the loss of carbonylated proteins, whereas providing soybean xylem sap via the transpiration stream effectively prevented degradation. The effect of xylem sap was mimicked by feeding 10 μM kinetin. We postulate that disruption of cytokinin flux to detached leaves triggers the selective degradation of carbonylated proteins via the proteasome pathway. The results may have implications for the control of protein mobilization in response to changes in N availability.

Keywords: Arabidopsis; Autophagy; Cytokinin; Protein carbonylation; Protein degradation; Proteasomes

Journal Article.  5320 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.