J-Domain Protein CDJ2 and HSP70B Are a Plastidic Chaperone Pair That Interacts with Vesicle-Inducing Protein in Plastids 1
AUTOR(ES)
Liu, Cuimin
FONTE
The American Society for Cell Biology
RESUMO
J-domain cochaperones confer functional specificity to their heat shock protein (HSP)70 partner by recruiting it to specific substrate proteins. To gain insight into the functions of plastidic HSP70s, we searched in Chlamydomonas databases for expressed sequence tags that potentially encode chloroplast-targeted J-domain cochaperones. Two such cDNAs were found: the encoded J-domain proteins were named chloroplast DnaJ homolog 1 and 2 (CDJ1 and CDJ2). CDJ2 was shown to interact with a ∼28-kDa protein that by mass spectrometry was identified as the vesicle-inducing protein in plastids 1 (VIPP1). In fractionation experiments, CDJ2 was detected almost exclusively in the stroma, whereas VIPP1 was found in low-density membranes, thylakoids, and in the stroma. Coimmunoprecipitation and mass spectrometry analyses identified stromal HSP70B as the major protein interacting with soluble VIPP1, and, as confirmed by cross-linking data, as chaperone partner of CDJ2. In blue native-PAGE of soluble cell extracts, CDJ2 and VIPP1 comigrated in complexes of >>669, ∼150, and perhaps ∼300 kDa. Our data suggest that CDJ2, presumably via coiled-coil interactions, binds to VIPP1 and presents it to HSP70B in the ATP state. Our findings and the previously reported requirement of VIPP1 for the biogenesis of thylakoid membranes point to a role for the HSP70B/CDJ2 chaperone pair in this process.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=551482Documentos Relacionados
- Role of the J-domain in the cooperation of Hsp40 with Hsp70
- HEAT SHOCK PROTEIN 90C Is a Bona Fide Hsp90 That Interacts with Plastidic HSP70B in Chlamydomonas reinhardtii1
- A Cellular J-Domain Protein Modulates Polyprotein Processing and Cytopathogenicity of a Pestivirus
- An Auxilin-Like J-Domain Protein, JAC1, Regulates Phototropin-Mediated Chloroplast Movement in Arabidopsis1[w]
- OWL1: An Arabidopsis J-Domain Protein Involved in Perception of Very Low Light Fluences[W]