Entry URI http://metadb.riken.jp/db/SciNetS_ria224i/cria224u4ria224u15516497i
Entry name Constan Diane et al. 2004 Nov. Plant Physiol. 136(3):3605-15.
Title A stromal Hsp100 protein is required for normal chloroplast development and function in Arabidopsis.
Authors Constan Diane|Froehlich John E|Keegstra Kenneth|Rangarajan Sowkya
Abstract Molecular chaperones are required for the translocation of many proteins across organellar membranes, presumably by providing energy in the form of ATP hydrolysis for protein movement. In the chloroplast protein import system, a heat shock protein 100 (Hsp100), known as Hsp93, is hypothesized to be the chaperone providing energy for precursor translocation, although there is little direct evidence for this hypothesis. To learn more about the possible function of Hsp93 during protein import into chloroplasts, we isolated knockout mutant lines that contain T-DNA disruptions in either atHSP93-V or atHSP93-III, which encode the two Arabidopsis (Arabidopsis thaliana) homologs of Hsp93. atHsp93-V mutant plants are much smaller and paler than wild-type plants. In addition, mutant chloroplasts contain less thylakoid membrane when compared to the wild type. Plastid protein composition, however, seems to be largely unaffected in atHsp93-V knockout plants. Chloroplasts isolated from the atHsp93-V knockout mutant line are still able to import a variety of precursor proteins, but the rate of import of some of these precursors is significantly reduced. These results indicate that atHsp93-V has an important, but not essential, role in the biogenesis of Arabidopsis chloroplasts. In contrast, knockout mutant plants for atHsp93-III, the second Arabidopsis Hsp93 homolog, had a visible phenotype identical to the wild type, suggesting that atHsp93-III may not play as important a role as atHsp93-V in chloroplast development and/or function.
Pubmed ID 15516497
Journal Plant physiology
Volume 136
Issue 3
Pages 3605-15
Publication date 2004 Nov
Num of phenotype gene 2