Cytokinin stimulates polyribosome loading of nuclear‐encoded mRNAs for the plastid ATP synthase in etioplasts of Lupinus luteus: the complex accumulates in the inner‐envelope membrane with the CF₁ moiety located towards the stromal space

Abstract

SummaryThree of the nine subunits of the plastid ATP synthase, including the subunit of the CF 1 moiety (gene AtpC ), are encoded in the nucleus. Application of cytokinin to etiolated lupine seedlings induces polyribosome association of their mRNAs. This appears to be speci®c as no such regulation was observed for messages for three ribosomal proteins. Cytokinin-mediated polyribosome loading was also observed for the spinach AtpC message in etiolated transgenic tobacco seedlings. Analysis of various spinach AtpC mRNA derivatives uncovered that the 5 H untranslated region (5 H UTR) of this message is suf®cient to direct polyribosome loading, and that sequences at the 3 H end of the AtpC 5 H UTR, including an UC-rich motif, are crucial for this regulation. The increase in polyribosome loading of the AtpC message correlated with an increased synthesis of the polypeptide. The subunit, together with the ATP synthase complex, accumulates in the innerenvelope membrane with the CF 1 moiety located towards the stromal space of the etioplast. These results suggest that cytokinin promotes accumulation of the ATP synthase in the inner-envelope membrane of lupine etioplasts by stimulating the translation ef®ciency of their nuclear-encoded messages.

Improved antigen retrieval in freeze-fracture cytochemistry by evaporation of carbon as first replication layer

“…5d in Fujimoto et al 1996). The evaporation eVect was also visible in localization experiments of the CF 1 subunit of plastid ATP synthase in etioplast membranes of Lupinus luteus (Figure 9a in Sherameti et al 2004). Here, the most labeling was found in areas of thin platinum deposition at the PF of the inner etioplast-envelope membrane.…”

“…In recent investigations we labeled many diVerent proteins using the method of SDS freeze-fracture cytochemistry (Peskan et al 2000;Galle et al 2002;Pop et al 2003;Sherameti et al 2004;Westermann and Rhiel 2005). We made the experience that white or bright appearing replica areas with thin or even no platinum deposition (platinum shadows) show equal or higher labeling eYciencies than regions consisting of mixed Pt/C.…”

Knock-out of the Plastid-encoded PetL Subunit Results in Reduced Stability and Accelerated Leaf Age-dependent Loss of the Cytochrome b6f Complex

“…The ATP synthase, which seems to be subject to a similar leaf-age dependent downregulation as the Cyt-bf complex (Fig. 6), is strongly regulated by cytokinins at the translational level (48). This suggests that hormonal gradients across the plants can directly determine the rate of photosynthetic complex biogenesis.…”

Cytokinin effects on tetrapyrrole biosynthesis and photosynthetic activity in barley seedlings

“…5,6). Several plastid-localized, in particular photosynthetic, enzymes were shown to be activated by cytokinin in dark-grown seedlings, like ribulose 1,5-bisphosphate carboxylase/oxygenase (Feierabend 1969;Harvey et al 1974), NADP-glyceraldehydephosphate dehydrogenase (Feierabend 1969;Harvey et al 1974), ATP synthase (Kasten et al 1997;Kusnetsov et al 1999;Sherameti et al 2004), nitrate reductase (Rao et al 1984) and phosphoglycerate kinase (Kasten et al 1997). More recently, many genes were found to be cytokinin-induced in light-grown seedlings (Hoth et al 2003).…”