The role of cytochrome bss9 in photosynthesis has remained enigmatic despite considerable efforts to elucidate its function [ 11. Some experiments show that cytochrome bss9 is closely associated with the oxidizing side of photosystem II, others indicate redox activity between the two photosystems, while still others suggest participation in a cycle around photosystem II. Part of the enigma of c...

Genes of the HSP70 chaperone family are induced by light. In Chlamydomonas reinhardtii, the induction of HSP70 (70 kDa heat shock protein) chaperones by light results in a partial protection of photosystem II against damage by photoinhibitory conditions. Underexpression of a chloroplast-localized HSP70 protein caused an increased sensitivity of photosystem II to light. Overexpression of this pr...

The protein composition o f Chlamydomonas reinhardii thylakoids in the molecular weight range of 3 2 -3 5 kDa was studied. The thylakoids were labelled with 32P—Pj in vivo using Prstarved cell cultures, solubilized with SDS and separated by polyacrylam ide gradient gel electrophoresis. The following differentiation of proteins could be accomplished: two proteins were phosphorylated, which were ...

In the Phaeodactylum tricornutum alga, as in most diatoms, cytochrome c6 is the only electron donor to photosystem I, and thus they lack plastocyanin as an alternative electron carrier. We have investigated, by using laser-flash absorption spectroscopy, the electron transfer to Phaeodactylum photosystem I from plastocyanins from cyanobacteria, green algae and plants, as compared with its own cy...

A third group o f antibiotics, the aurachins, have been isolated from the m yxobacterium Stigmatella aurantiaca. The aurachins chemically are quinolones, and four o f them (aurachins A D ) have been tested for their inhibitory activity in photosystem II and cytochrom e b/ccomplexes. A urachin C is the best inhibitor in photosystem II (p /50-value 7.2); its biochemical behaviour being the same l...

The concept that the two photosystems of photosynthesis cooperate in series, immortalized in Hill and Bendall's Z scheme, was still a black box that defined neither the structural nor the molecular organization of the thylakoid membrane network into grana and stroma thylakoids. The differentiation of the continuous thylakoid membrane into stacked grana thylakoids interconnected by single stroma...

Chloroplasts isolated from pea seadlings grown on water containing 45Ca2+ were treated with local anesthetic tetracaine. Addition of tetracaine inactivated the electron transport activity of donor side photosystem II. This inhibition was accompanied by 45Ca2+ release from the chloroplast membranes as the whole and destroyed by osmotic shock. No such effect was observed when Tris or hydroxylamin...

We report a structural characterization by electron microscopy of green plant photosystem I solubilized by the mild detergent n-dodecyl-alpha-D-maltoside. It is shown by immunoblotting that the isolated complexes contain all photosystem I core proteins and all peripheral light-harvesting proteins. The electron microscopic analysis is based on a large data set of 14 000 negatively stained single...

M aria Teresa Giardi Institute of Biochemistry and Ecophysiology of Plants, C N R Area della ricerca di Roma, Via Salaria km 29.3, 00016 M onterotondo Scalo, Italy Z. Naturforsch. 48c, 241 2 4 5 (1993); received November 9, 1992 Photosystem II Core, Phosphorylation, Heterogeneity, Phosphatase, Herbicide-Binding Domain In recent papers the heterogeneous nature of photosystem (PS) II core phospho...

We have examined the photophysics of energy migration and trapping in photosystem I by investigating the spectral and temporal properties of the fluorescence from the core antenna chlorophylls as a function of the antenna size. Time-correlated single photon counting was used to determine the fluorescence lifetimes in the isolated P700 chlorophyll a-protein complex and in a mutant of Chlamydomon...