Lysyl oxidase-like protein secreted from an acidophilic red alga, .

is a primitive acidophilic red alga which grown optimally at pH 1-3. When the alga was cultured at pH 6, which is the upper limit of acidity for its survival, most of the algal cells became large cells with four endospores which did not split into daughter cells. This suggests that the alga survives in the endospore state at pH 6 to protect against nutrient uptake deficiency due to low pH gradient across the cell membranes.

Conversion of photosystem II dimer to monomers during photoinhibition is tightly coupled with decrease in oxygen-evolving activity in the diatom Chaetoceros gracilis.

The rapid turnover of photosystem II (PSII) in diatoms is thought to be at an exceptionally high rate compared with other oxyphototrophs; however, its molecular mechanisms are largely unknown. In this study, we examined the photodamage and repair processes of PSII in the marine centric diatom Chaetoceros gracilis incubated at 30 or 300 μmol photons m s in the presence of a de novo protein-synthesis inhibitor. When de novo protein synthesis was blocked by chloramphenicol (Cm), oxygen-evolving activity gradually decreased even at 30 μmol photons m s and could not be detected at 12 h.

Novel Features of Eukaryotic Photosystem II Revealed by Its Crystal Structure Analysis from a Red Alga.

Photosystem II (PSII) catalyzes light-induced water splitting, leading to the evolution of molecular oxygen indispensible for life on the earth. The crystal structure of PSII from cyanobacteria has been solved at an atomic level, but the structure of eukaryotic PSII has not been analyzed. Because eukaryotic PSII possesses additional subunits not found in cyanobacterial PSII, it is important to solve the structure of eukaryotic PSII to elucidate their detailed functions, as well as evolutionary relationships.

Crystal structure of Psb31, a novel extrinsic protein of photosystem II from a marine centric diatom and implications for its binding and function.

Psb31 is a fifth extrinsic protein found in photosystem II (PSII) of a centric diatom, Chaetoceros gracilis . The protein has been shown to bind directly to PSII in the absence of other extrinsic proteins and serves in part as a substitute for PsbO in supporting oxygen evolution. We report here the crystal structure of Psb31 at a resolution of 1.

Light-independent biosynthesis and assembly of the photosystem II complex in the diatom Chaetoceros gracilis.

Diatoms can survive for long periods in the dark. However, how biosynthesis of photosynthetic proteins contributes to survival in the dark is poorly understood. Using a radiolabeling technique, we examined whether de novo biosynthesis and assembly of photosynthetic proteins differs in light-adapted vs.

Proteases are associated with a minor fucoxanthin chlorophyll a/c-binding protein from the diatom, Chaetoceros gracilis.

We previously showed that most subunits in the oxygen-evolving photosystem II (PSII) preparation from the diatom Chaetoceros gracilis are proteolytically unstable. Here, we focused on identifying the proteases that cleave PSII subunits in thylakoid membranes. Major PSII subunits and fucoxanthin chlorophyll (Chl) a/c-binding proteins (FCPs) were specifically degraded in thylakoid membranes.

Binding and functional properties of five extrinsic proteins in oxygen-evolving photosystem II from a marine centric diatom, Chaetoceros gracilis.

Oxygen-evolving photosystem II (PSII) isolated from a marine centric diatom, Chaetoceros gracilis, contains a novel extrinsic protein (Psb31) in addition to four red algal type extrinsic proteins of PsbO, PsbQ', PsbV, and PsbU. In this study, the five extrinsic proteins were purified from alkaline Tris extracts of the diatom PSII by anion and cation exchange chromatographic columns at different pH values. Reconstitution experiments in various combinations with the purified extrinsic proteins showed that PsbO, PsbQ', and Psb31 rebound directly to PSII in the absence of other extrinsic proteins, indicating that these extrinsic proteins have their own binding sites in PSII intrinsic proteins.

Topological analysis of the extrinsic PsbO, PsbP and PsbQ proteins in a green algal PSII complex by cross-linking with a water-soluble carbodiimide.

The close association of the extrinsic PsbO, PsbP and PsbQ proteins with PSII core subunits in oxygen-evolving PSII complexes from a green alga, Chlamydomonas reinhardtii, was examined by cross-linking experiments with a water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). The green algal PSII complexes treated with EDC were washed with alkaline Tris to remove the non-cross-linked extrinsic proteins, and then applied to Blue-Native-PAGE to prepare PSII core complexes. The extrinsic proteins cross-linked with PSII core complexes were detected by immunoblotting analysis using antibodies against extrinsic proteins and PSII core subunits.

Purification and characterization of a stable oxygen-evolving Photosystem II complex from a marine centric diatom, Chaetoceros gracilis.

Oxygen-evolving Photosystem II particles (crude PSII) retaining a high oxygen-evolving activity have been prepared from a marine centric diatom, Chaetoceros gracilis (Nagao et al., 2007). The crude PSII, however, contained a large amount of fucoxanthin chlorophyll a/c-binding proteins (FCP).

Plugging a molecular wire into photosystem I: reconstitution of the photoelectric conversion system on a gold electrode.

Plug and play: Photoinduced electron transfer occurs from photoexcited P700 in photosystem I (PSI) to a gold surface (see picture). A novel molecular connector system is used, in which an artificial molecular wire, which is assembled on the gold surface, was plugged into PSI by reconstitution. Analysis of the photoelectron transfer kinetics proved both the output of electrons from PSI and the effectiveness of the molecular wire.

Towards structural elucidation of eukaryotic photosystem II: Purification, crystallization and preliminary X-ray diffraction analysis of photosystem II from a red alga.

Crystal structure of photosystem II (PSII) has been reported from prokaryotic cyanobacteria but not from any eukaryotes. In the present study, we improved the purification procedure of PSII dimers from an acidophilic, thermophilic red alga Cyanidium caldarium, and crystallized them in two forms under different crystallization conditions. One had a space group of P222(1) with unit cell constants of a=146.

A novel protein in Photosystem II of a diatom Chaetoceros gracilis is one of the extrinsic proteins located on lumenal side and directly associates with PSII core components.

The gene encoding a novel extrinsic protein (Psb31) found in Photosystem II (PSII) of a diatom, Chaetoceros gracilis, was cloned and sequenced. The deduced protein contained three characteristic leader sequences targeted for chloroplast endoplasmic reticulum membrane, chloroplast envelope membrane and thylakoid membrane, indicating that Psb31 is encoded in the nuclear genome and constitutes one of the extrinsic proteins located on the lumenal side. Homologous genes were found in a red alga and chromophytic algae but not in other organisms.

Structures and functions of the extrinsic proteins of photosystem II from different species.

This minireview presents a summary of information available on the variety and binding properties of extrinsic proteins that form the oxygen-evolving complex of photosystem II (PSII) of cyanobacteria, red alga, diatom, green alga, euglena, and higher plants. In addition, the structure and function of extrinsic PsbO, PsbV, and PsbU proteins are summarized based on the crystal structure of thermophilic cyanobacterial PSII together with biochemical and genetic studies from various organisms.

A brief introduction of Kimiyuki Satoh.

In this Special Issue of Photosynthesis Research (Structure, Function, and Dynamics of Photosystem II) in honor of Kimiyuki Satoh and Thomas J. Wydrzynski, we present here a brief introduction to the scientific career and achievements of Kimiyuki Satoh, a great scientist with numerous important contributions in photosynthesis research, especially in the field of photosystem II.

Isolation and characterization of oxygen-evolving thylakoid membranes and photosystem II particles from a marine diatom Chaetoceros gracilis.

Thylakoid membranes retaining high oxygen-evolving activity (about 250 micromol O(2)/mg Chl/h) were prepared from a marine centric diatom, Chaetoceros gracilis, after disruption of the cells by freeze-thawing. We also succeeded in purification of Photosystem II (PSII) particles by differential centrifugation of the thylakoid membranes after treatment with 1% Triton X-100. The diatom PSII particles showed an oxygen-evolving activity of 850 and 1045 micromol O(2)/mg Chl/h in the absence and presence of CaCl(2), respectively.

Aromatic structure of tyrosine-92 in the extrinsic PsbU protein of red algal photosystem II is important for its functioning.

PsbU is one of the extrinsic proteins in red algal Photosystem II (PSII) and functions to optimize the availability of Ca(2+) and Cl(-) cofactors for water oxidation. To determine the functional residue of PsbU, we constructed various PsbU mutants from a red alga Cyanidium caldarium and reconstituted these mutants with the red algal PSII. The results revealed that Tyr-92 of PsbU, especially its aromatic ring, was essential for maintaining its function.

Quality control of Photosystem II: cleavage and aggregation of heat-damaged D1 protein in spinach thylakoids.

Moderate heat stress (40 degrees C, 30 min) on spinach thylakoids induced cleavage of the D1 protein, producing an N-terminal 23-kDa fragment, a C-terminal 9-kDa fragment, and aggregation of the D1 protein. A homologue of Arabidopsis FtsH2 protease, which is responsible for degradation of the damaged D1 protein, was abundant in the stroma thylakoids. Two processes occurred in the thylakoids in response to heat stress: dephosphorylation of the D1 protein in the stroma thylakoids, and aggregation of the phosphorylated D1 protein in the grana.

Bio-photosensor: Cyanobacterial photosystem I coupled with transistor via molecular wire.

We report on the first successful output of electrons directly from photosystem I (PSI) of thermophilic cyanobacteria to the gate of a field-effect transistor (FET) by bypassing electron flow via a newly designed molecular wire, i.e., artificial vitamin K(1), and a gold nanoparticle; in short, this newly manufactured photosensor employs a bio-functional unit as the core of the device.

Distribution of the extrinsic proteins as a potential marker for the evolution of photosynthetic oxygen-evolving photosystem II.

Distribution of photosystem II (PSII) extrinsic proteins was examined using antibodies raised against various extrinsic proteins from different sources. The results showed that a glaucophyte (Cyanophora paradoxa) having the most primitive plastids contained the cyanobacterial-type extrinsic proteins (PsbO, PsbV, PsbU), and the primitive red algae (Cyanidium caldarium) contained the red algal-type extrinsic proteins (PsO, PsbQ', PsbV, PsbU), whereas a prasinophyte (Pyraminonas parkeae), which is one of the most primitive green algae, contained the green algal-type ones (PsbO, PsbP, PsbQ). These suggest that the extrinsic proteins had been diverged into cyanobacterial-, red algal- and green algal-types during early phases of evolution after a primary endosymbiosis.

Identification of genes expressed in response to acid stress in Synechocystis sp. PCC 6803 using DNA microarrays.

Plant cells are always exposed to various environmental stresses such as high light, low temperature and acid rain, and thus have to respond in order to survive these stresses. Although some mechanisms of responses to high light and low temperature etc., have been clarified, there is little information about the acclimation process to acid stress.

Isolation and characterization of oxygen-evolving photosystem II complexes retaining the PsbO, P and Q proteins from Euglena gracilis.

Oxygen-evolving photosystem II (PSII) complexes of Euglena gracilis were isolated and characterized. (1) The PSII complexes contained three extrinsic proteins of 33 kDa (PsbO), 23 kDa (PsbP) and 17 kDa (PsbQ), and showed oxygen-evolving activity of around 700 micromol O2 (mg Chl)(-1) h(-1) even in the absence of Cl- and Ca2+ ions. (2) NaCl-treatment removed not only PsbP and PsbQ but also a part of PsbO from Euglena PSII, indicating that PsbO binds to Euglena PSII more loosely than those of other organisms.

Identification of domains on the extrinsic 23 kDa protein possibly involved in electrostatic interaction with the extrinsic 33 kDa protein in spinach photosystem II.

To elucidate the domains on the extrinsic 23 kDa protein involved in electrostatic interaction with the extrinsic 33 kDa protein in spinach photosystem II, we modified amino or carboxyl groups of the 23 kDa protein to uncharged methyl ester groups with N-succinimidyl propionate or glycine methyl ester in the presence of a water-soluble carbodiimide, respectively. The N-succinimidyl propionate-modified 23 kDa protein did not bind to the 33 kDa protein associated with PSII membranes, whereas the glycine methyl ester-modified 23 kDa protein completely bound. This indicates that positive charges on the 23 kDa protein are important for electrostatic interaction with the 33 kDa protein associated with the PSII membranes.

Extrinsic proteins of photosystem II: an intermediate member of PsbQ protein family in red algal PS II.

The oxygen-evolving photosystem II (PS II) complex of red algae contains four extrinsic proteins of 12 kDa, 20 kDa, 33 kDa and cyt c-550, among which the 20 kDa protein is unique in that it is not found in other organisms. We cloned the gene for the 20-kDa protein from a red alga Cyanidium caldarium. The gene consists of a leader sequence which can be divided into two parts: one for transfer across the plastid envelope and the other for transfer into thylakoid lumen, indicating that the gene is encoded by the nuclear genome.

Comparison of binding and functional properties of two extrinsic components, Cyt c550 and a 12 kDa protein, in cyanobacterial PSII with those in red algal PSII.

Cyt c550 and 12 kDa protein are two extrinsic proteins of photosystem II (PSII) found in cyanobacteria and some eukaryotic algae. The binding patterns of these two extrinsic proteins are different between cyanobacterial (Thermosynechococcus vulcanus) and red algal (Cyanidium caldarium) PSIIs [Shen and Inoue (1993) Biochemistry 32: 1825; Enami et al. (1998) Biochemistry 39: 2787].

Binding and functional properties of the extrinsic proteins in oxygen-evolving photosystem II particle from a green alga, Chlamydomonas reinhardtii having his-tagged CP47.

Oxygen-evolving photosystem II (PSII) particles were purified from Chlamydomonas reinhardtii having His-tag extension at the C terminus of the CP47 protein, by a single-step Ni(2+)-affinity column chromatography after solubilization of thylakoid membranes with sucrose monolaurate. The PSII particles consisted of, in addition to intrinsic proteins, three extrinsic proteins of 33, 23 and 17 kDa. The preparation showed a high oxygen-evolving activity of 2,300-2,500 micro mol O(2) (mg Chl)(-1) h(-1) in the presence of Ca(2+) using ferricyanide as the electron acceptor, while its activity was 680-720 micro mol O(2) (mg Chl)(-1) h(-1) in the absence of Ca(2+) and Cl(-) ions.