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.