394
Entry URI http://metadb.riken.jp/db/SciNetS_ria224i/cria224u4ria224u16766689i
Entry name Rudella Andrea et al. 2006 Jul. Plant Cell 18(7):1704-21.
Title Downregulation of ClpR2 leads to reduced accumulation of the ClpPRS protease complex and defects in chloroplast biogenesis in Arabidopsis.
Authors Alonso Jose M|Ecker Joseph R|Friso Giulia|Rudella Andrea|van Wijk Klaas J
Abstract Plastids contain tetradecameric Clp protease core complexes, with five ClpP Ser-type proteases, four nonproteolytic ClpR, and two associated ClpS proteins. Accumulation of total ClpPRS complex decreased twofold to threefold in an Arabidopsis thaliana T-DNA insertion mutant in CLPR2 designated clpr2-1. Differential stable isotope labeling of the ClpPRS complex with iTRAQ revealed a fivefold reduction in assembled ClpR2 accumulation and twofold to fivefold reductions in the other subunits. A ClpR2:(his)(6) fusion protein that incorporated into the chloroplast ClpPRS complex fully complemented clpr2-1. The reduced accumulation of the ClpPRS protease complex led to a pale-green phenotype with delayed shoot development, smaller chloroplasts, decreased thylakoid accumulation, and increased plastoglobule accumulation. Stromal ClpC1 and 2 were both recruited to the thylakoid surface in clpr2-1. The thylakoid membrane of clpr2-1 showed increased carotenoid content, partial inactivation of photosystem II, and upregulated thylakoid proteases and stromal chaperones, suggesting an imbalance in chloroplast protein homeostasis and a well-coordinated network of proteolysis and chaperone activities. Interestingly, a subpopulation of PsaF and several light-harvesting complex II proteins accumulated in the thylakoid with unprocessed chloroplast transit peptides. We conclude that ClpR2 cannot be functionally replaced by other ClpP/R homologues and that the ClpPRS complex is central to chloroplast biogenesis, thylakoid protein homeostasis, and plant development.
Pubmed ID 16766689
Journal The Plant cell
Volume 18
Issue 7
Pages 1704-21
Publication date 2006 Jul
Num of phenotype gene 2