Chloroplast DnaJ-like proteins 3 and 4 (CDJ3/4) from Chlamydomonas reinhardtii contain redox-active Fe-S clusters and interact with stromal HSP70B

International audienceIn this study we report on the identification and characterization of three novel chloroplast-targeted J-domain proteins, CDJ3-5, which in addition to their J-domains contain bacterial-type ferredoxin domains. In the databases we could identify homologs of CDJ3-5 in green algae, moss and higher plants, but not in cyanobacteria. Phylogenetic analyses allowed distinguishing two clades containing CDJ3/4 and CDJ5 that must have diverged early in an ancestor of the green lineage and have further diversified later on. Molecular and biochemical analysis of CDJ3 and CDJ4 from Chlamydomonas reinhardtii revealed that both are weakly expressed proteins that appear to be localized to the stroma and to thylakoid membranes, respectively. The low transcript levels of the CDJ3 and CDJ4 genes declined even further in the initial phase of heat shock, but CDJ3 transcript levels strongly increased after dark-to-light shift. Accordingly, the Arabidopsis ortholog of CDJ5 was also found to be light inducible and to be under strong circadian control. CDJ3 and CDJ4 proteins could both be expressed in Escherichia coli with redox-active Fe-S clusters. In vitro crosslinking studies demonstrated that CDJ3 and CDJ4 interact with chloroplast HSP70B in the ATP state, presumably as dimers, and immunoprecipitation studies showed that CDJ3/4 were in common complexes with HSP70B also in Chlamydomonas cell extracts. Finally, CDJ3 was found in complexes with apparent molecular masses of ~550 to 2800 kDa that appeared to contain RNA. We speculate that CDJ3-5 might represent redox switches that act by recruiting HSP70B for the reorganization of regulatory protein complexes

Large Housing Estates of Berlin, Germany

Large estates of towers and slabs can be found all over the German capital, and the differences between those which before 1990 were situated on different sides of the Berlin Wall are often hard to tell for the layperson. They stand witness to the dream of modern living and acceptable housing conditions for the whole population, which in the decades after the Second World War inspired the socialist regime in the East in the same way as the welfare state in the West. In terms of political background and social significance, however, the Plattenbauten (slab buildings) in the East were rather distinct from the Wohnblöcke (dwelling blocks) in the West. Not only were those in the East far more frequent – in 1990 about one third of East Berliners call a large housing estate their home, compared to about only five percent of West Berliners – they also constituted an environment that was closely aligned to the East German regime’s socio-political goals. This chapter will summarize the history of large housing estates in both East and West Berlin, pointing out commonalities and differences that determine significance and perception of these buildings to date