Poster: Organelle biogenesis

Abs # 627: Characterization of the Clp Protease Complex in Arabidopsis Plastids through Reverse Genetics and Biochemistry

Presenter:	Rudella, Andrea , ar253@cornell.edu
Authors	Rudella, Andrea  (A)   Patel, Kieren J (A)   Peltier, Jean-Benoit  (A)   van Wijk, Klaas J (A)
Affiliations:	(A): Plant Biology, Cornell University
Web Site:	http://cbsu.tc.cornell.edu/vanwijk/

Proteolysis in the plastid is important to control protein processing, stoichiometry, housekeeping, and regulation of plastid gene expression. The Clp complex in higher plant plastids consists of a proteolytic core with nine different ClpP,R proteins and several associated chaperone-like proteins. One of the Clp genes is plastid-encoded and is essential in tobacco for shoot development. Using biochemical techniques, we have recently demonstrated that amyloplasts, leucoplasts and chloroplasts all seem to contain a single 325 kDa core complex with nine ClpP/R proteins and 2 chaperone-like ClpS proteins. In contrast, mitochondria contain a homo-tetradecameric ClpP2 complex (Peltier, et al. (2004), J Biol Chem, 279: 4768-81). A reverse genetics approach has been undertaken to characterize the functional complexity of the A. thaliana plastid Clp family. Isolation of T-DNA insertion mutants for nuclear encoded Clp genes suggests that the core subunits are essential, whereas the chaperone subunits are functionally redundant. TEM analysis reveals that thylakoids biogenesis is highly affected when ClpP/R genes are disrupted. Data regarding selected T-DNA insertion lines will be presented.