Throughout their life cycle, plants undergo a number of essential developmental transitions while they are exposed to constantly changing environments. Since plants are immobile, they have to ensure their survival through rapid adoption to these environmental changes. In eukaryotes, rapid growth responses can be achieved by the rapid degradation of regulatory proteins such as transcriptional activators, transcriptional repressors, and cell cycle regulators via the ubiquitin-proteasome system. In this process, proteins destined for degradation are identified through the attachment of ubiquitin (a small protein) chains prior to their proteolysis by the 26S proteasome (a multiprotein complex). Several percent of the Arabidopsis proteome represent proteins with homology to known components of the ubiquitin-proteasome system. This by far exceeds the relative number of ubiquitin-proteasome-related proteins from non-plant organisms and suggests that protein degradation is a predominant regulatory mechanism in plant growth and development. However, relatively little is known about the biological and biochemical function of most of these proteins. Through the integration of genetics, molecular biology and cell biology with genomics and proteomics, we are addressing a number of questions related to the ubiquitin-proteasome system in plants.

Relevant reference:

Claus Schwechheimer and Luz Irina A Calderón-Villalobos (2004). Current Opinion in Plant Biology 7: 677 - 686. PubMed