Report: Qihua Ling Weihua Huang Amy Baldwin Paul Jarvis. Chloroplast Biogenesis Is Regulated by Direct Action of the Ubiquitin-Proteasome System. Science 2012 338 (6107): 655-659 DOI: 10.1126-science.1225053
Abstract
Development of chloroplasts and other plastids depends on the import of thousands of nucleus-encoded proteins from the cytosol. Import is initiated by TOC (translocon at the outer envelope of chloroplasts) complexes in the plastid outer membrane that incorporate multiple client-specific receptors. Modulation of import is thought to control the plastid’s proteome developmental fate and functions. Using forward genetics we identified Arabidopsis SP1 which encodes a RING-type ubiquitin E3 ligase of the chloroplast outer membrane. The SP1 protein associated with TOC complexes and mediated ubiquitination of TOC components promoting their degradation. Mutant sp1 plants performed developmental transitions that involve plastid proteome changes inefficiently indicating a requirement for reorganization of the TOC machinery. Thus the ubiquitin-proteasome system acts on plastids to control their development.
Report: J. Lorang T. Kidarsa C. S. Bradford B. Gilbert M. Curtis S.-C. Tzeng C. S. Maier T. J. Wolpert. Tricking the Guard: Exploiting Plant Defense for Disease Susceptibility. Science 2012:
