Hisashi Itô 교수

GSH has multiple actions in physiological responses of plants, but the molecular mechanisms are not fully understood. GSH plays an important role in functional alteration of proteins by reversible covalent incorporation (glutathionylation) in vertebrate cells. To investigate the function of glutathionylation in plant cells, we examined glutathionylated proteins in the suspension-cultured cells of Arabidopsis using biotinylated GSH. Biotinylated GSH was incorporated into about 20 proteins. Two of

Chlorophyll b is synthesized from chlorophyll a by the oxidation of the methyl group on the ring B of the tetrapyrrole ring to the formyl group. Previously, we reported that chlorophyllide b could be converted to chlorophyll a in isolated cucumber etioplasts indicating the conversion of chlorophyll b to chlorophyll a. To identify the intermediate molecule, we used barley etioplasts instead of cucumber. Chlorophyll a and an additional pigment were found after incubation of chlorophyllide b with i

The vast majority of oxygenic photosynthetic organisms use monovinyl chlorophyll for their photosynthetic reactions. For the biosynthesis of this type of chlorophyll, the reduction of the 8-vinyl group that is located on the B-ring of the macrocycle is essential. Previously, we identified the gene encoding 8-vinyl reductase responsible for this reaction in higher plants and termed it DVR. Among the sequenced genomes of cyanobacteria, only several Synechococcus species contain DVR homologues. The

Research on chlorophyll degradation has progressed significantly in recent decades. In the 1990s, the structure of linear tetrapyrrole, which is unambiguously a chlorophyll degradation product, was determined. From the 2000s until the 2010s, the major enzymes involved in chlorophyll degradation were identified, and the pheophorbide a oxygenase/phyllobilin pathway was established. This degradation pathway encompasses several steps: (i) initial conversion of chlorophyll b to 7-hydroxymethyl chloro

Chlorophyll a accumulated when chlorophyllide b was incubated with isolated cucumber etioplasts in the dark. When [14C]chlorophyllide b was used as the substrate for chlorophyll synthesis, [14C]chlorophyll a was formed, showing that chlorophyll a was synthesized from the exogenously added chlorophyllide b, not by light-independent reduction of endogenous protochlorophyllide. The reaction studied showed an optimal pH of 7.5 and required both the soluble and membrane fractions of etioplasts togeth

Chlorophyll is a deleterious molecule that generates reactive oxygen species and must be converted to nontoxic molecules during plant senescence. The degradation pathway of chlorophyll a has been determined; however, that of chlorophyll b is poorly understood, and multiple pathways of chlorophyll b degradation have been proposed. In this study, we found that chlorophyll b is degraded by a single pathway, and elucidated the importance of this pathway in avoiding cell death. In order to determine

Organisms generate an enormous number of metabolites; however, the mechanisms by which a new metabolic pathway is acquired are unknown. To elucidate the importance of promiscuous enzyme activity for pathway evolution, the catalytic and substrate specificities of Chl biosynthetic enzymes were examined. In green plants, Chl a and Chl b are interconverted by the Chl cycle: Chl a is hydroxylated to 7-hydroxymethyl chlorophyll a followed by the conversion to Chl b, and both reactions are catalyzed by

Acquisition of new photosynthetic pigments has been a crucial process for the evolution of photosynthesis and photosynthetic organisms. In this process, pigment-binding proteins must evolve to fit new pigments. Prochlorococcus is a unique photosynthetic organism that uses divinyl chlorophyll (DVChl) instead of monovinyl chlorophyll. However, cyanobacterial mutants that accumulate DVChl immediately die even under medium-light conditions, suggesting that chlorophyll (Chl)-binding proteins had to e

Studies on the constitution of silicate melts are very important not only in the fields of metallurgical processing or the glass industry, but also in dealing with the properties or constitution of liquids. For this reason a PbO-SiO2 system was chosen as a model of silicate or slag because of its low melting point and glass forming properties.As a result electrical conductivity measurements, it was found that the lead silicate melt had a positive temperature coefficient and ionic conductance lik

Chlorophyll a and chlorophyll b are interconverted in the chlorophyll cycle. The initial step in the conversion of chlorophyll b to chlorophyll a is catalyzed by the chlorophyll b reductases NON-YELLOW COLORING 1 (NYC1) and NYC1-like (NOL), which convert chlorophyll b to 7-hydroxymethyl chlorophyll a. This step is also the first stage in the degradation of the light-harvesting chlorophyll a/b protein complex (LHC). In this study, we examined the effect of chlorophyll b on the level of NYC1. NYC1